This work studied the microstructure,mechanical properties and damping properties of Mg_(95.34)Ni_(2)Y_(2.66) and Mg_(95.34)Zn_(1)Ni_(1)Y_(2.66)alloys systematically.The difference in the evolution of the long-period ...This work studied the microstructure,mechanical properties and damping properties of Mg_(95.34)Ni_(2)Y_(2.66) and Mg_(95.34)Zn_(1)Ni_(1)Y_(2.66)alloys systematically.The difference in the evolution of the long-period stacked ordered(LPSO)phase in the two alloys during heat treatment was the focus.The morphology of the as-cast Mg_(95.34)Ni_(2)Y_(2.66)presented a disordered network.After heat treatment at 773 K for 2 hours,the eutectic phase was integrated into the matrix,and the LPSO phase maintained the 18R structure.As Zn partially replaced Ni,the crystal grains became rounded in the cast alloy,and lamellar LPSO phases and more solid solution atoms were contained in the matrix after heat treatment of the Mg_(95.34)Zn_(1)Ni_(1)Y_(2.66)alloy.Both Zn and the heat treatment had a significant effect on damping.Obvious dislocation internal friction peaks and grain boundary internal friction peaks were found after temperature-dependent damping of the Mg_(95.34)Ni_(2)Y_(2.66)and Mg_(95.34)Zn_(1)Ni_(1)Y_(2.66)alloys.After heat treatment,the dislocation peak was significantly increased,especially in the alloy Mg_(95.34)Ni_(2)Y_(2).66.The annealed Mg_(95.34)Ni_(2)Y_(2.66)alloy with a rod-shaped LPSO phase exhibited a good damping performance of 0.14 atε=10^(−3),which was due to the difference between the second phase and solid solution atom content.These factors also affected the dynamic modulus of the alloy.The results of this study will help in further development of high-damping magnesium alloys.展开更多
Optimizing the mechanical properties and damping capacity of the duplex-structured Mg–Li–Zn–Mn alloy by tailoring the microstructure via hot extrusion was investigated.The results show that the Mg–8Li–4Zn–1Mn al...Optimizing the mechanical properties and damping capacity of the duplex-structured Mg–Li–Zn–Mn alloy by tailoring the microstructure via hot extrusion was investigated.The results show that the Mg–8Li–4Zn–1Mn alloy is mainly composed ofα-Mg,β-Li,Mg–Li–Zn and Mn phases.The microstructure of the test alloy is refined owing to dynamic recrystallization(DRX)during hot extrusion.After hot extrusion,the crushed precipitates are uniformly distributed in the test alloy.The yield strength(YS),ultimate tensile strength(UTS),and elongation(EL)of as-extruded alloy reach 156 MPa,208 MPa,and 32.3%,respectively,which are much better than that of as-cast alloy.Furthermore,the as-extruded and as-cast alloys both exhibit superior damping capacities,with the damping capacity(Q^(-1))of 0.030 and 0.033 at the strain amplitude of 2×10^(-3),respectively.The mechanical properties of the test alloy can be significantly improved by hot extrusion,whereas the damping capacities have no noticeable change,which indicates that the duplex-structured Mg–Li alloys with appropriate mechanical properties and damping properties can be obtained by alloying and hot extrusion.展开更多
The damping behaviors of Zn-Al alloys with fully lamellar microstructures were simulated with the cell method. The influences of the grain boundary condition, the strain amplitude, the number of the lamellae in the gr...The damping behaviors of Zn-Al alloys with fully lamellar microstructures were simulated with the cell method. The influences of the grain boundary condition, the strain amplitude, the number of the lamellae in the grain (N) and the content ratio of Zn and Al in Zn-Al alloys on the damping capacity were investigated. The results indicate that the grain boundary condition has great influence on the damping capacity of Zn-Al alloys, and also affects the relationship between the damping capacity and the number of lamellae (N). The variation of damping capacity with the strain amplitude is increasing exponentially with the strain amplitude and the damping capacity increases with the increasing of content of Zn.展开更多
The stress strain curves of two CuZnAl shape memory alloys which have the martensitic transformation temperatures of 50 ℃ and -10 ℃ respectively, were measured by using electronic material tester after treated by di...The stress strain curves of two CuZnAl shape memory alloys which have the martensitic transformation temperatures of 50 ℃ and -10 ℃ respectively, were measured by using electronic material tester after treated by different heat-treatment conditions. The results show that the area enclosed by hysteresis loop of the CuZnAl shape memory alloy in martensitic state is much larger than that of the alloy in austenitic state with super-elasticity at room temperature. Therefore, the former has better vibration attenuation effect. After being oil-quenched, water-quenched, and step-quenched, the CuZnAl alloy takes on more stable shape memory effect,better super-plasticity and superelasticity (pseudoelasticity). A CuZnAl shape memory alloy damper was designed, produced and installed to a 2-layer frame structure. In addition, the vibration experiments were made by dynamic data collecting analysis meter. The velocity of vibration attenuation of frame structure with CuZnAl shape memory alloy damper is much faster than that without it. And with the help of CuZnAl shape memory alloy damper, the attenuation period reduces to 1/10 of the original.展开更多
The damping properties of an Mg alloy foam and its composite foams were investigated using a dynamic mechanical thermal analyzer. The results show that the loss factors of both the Mg alloy and its composite foams are...The damping properties of an Mg alloy foam and its composite foams were investigated using a dynamic mechanical thermal analyzer. The results show that the loss factors of both the Mg alloy and its composite foams are insensitive to temperature and loading frequency when the temperature is less than a critical temperature Tcrit. However, it increases when the temperature exceeds the Tcrit values, which are 200 and 250°C for the Mg alloy foam and the Mg alloy/SiCp composite foams, respectively. The Mg alloy/SiCp composite foams exhibit a higher damping capacity than the Mg alloy foam when the temperature is below 200°C. By contrast, the Mg alloy foam exhibits a better damping capacity when the temperature exceeds 250°C. The variation in the damping capacity is attributed to differences in the internal friction sources, such as the characteristics of the matrix material, abundant interfaces, and interfacial slipping caused by SiC particles, as well as to macrodefects in the Mg alloy and its composite foams.展开更多
This paper investigated high-damping Cu-Al-Be-B cast alloys using metallographic analysis, X-ray diffraction (XRD) and electrical resistance measurements for transformation temperatures. The results showed that beryll...This paper investigated high-damping Cu-Al-Be-B cast alloys using metallographic analysis, X-ray diffraction (XRD) and electrical resistance measurements for transformation temperatures. The results showed that beryllium can stabilize β phase, resulting in a thermo-elastic martensite microstructure leading to high-damping capacity in cast Cu-Al-Be-B alloys. Trace additions of boron to Cu-Al-Be alloys can significantly refine the grains, providing high strength and ductility to the alloys. A factorial design of experiment method was used to optimize the composition and properties of cast Cu-Al-Be-B alloys. The optimal microstructure for thermo-elastic martensite can be obtained by adjusting the amounts of aluminum and beryllium to eutectoid or pseudo-eutectoid compositions. An optimized cast Cu-Al-Be-B alloy was developed to provide excellent mechanical properties, tensile strength σ_b=767MPa, elongation δ=7.62%, and damping capacity S. D. C=18.70%.展开更多
Microstructure observation and dynamic mechanical analysis were carried out to investigate the precipitation and responding damping behaviors of AZ31 magnesium alloy. All the strain amplitude-dependent damping curves ...Microstructure observation and dynamic mechanical analysis were carried out to investigate the precipitation and responding damping behaviors of AZ31 magnesium alloy. All the strain amplitude-dependent damping curves of the aged alloys are located between the curves of solutionized and as-cast alloys, although they have different critical strain amplitudes. The G-L theory is employed to explain the damping mechanism involving the interaction between the dislocation and the precipitated phase. In addition, a damping peak is observed at temperatures close to 330 ℃ for AZ31 magnesium alloy, which is related to the β-MglTA112 phase dissolution.展开更多
The modification mechanism and damping capacity(Q-1) of conventional ascast ZA27 alloy modified by Al10%RE were investigated. Cantilever beam technique was used to measure the damping capacity. The experimental result...The modification mechanism and damping capacity(Q-1) of conventional ascast ZA27 alloy modified by Al10%RE were investigated. Cantilever beam technique was used to measure the damping capacity. The experimental results show that the addition of RE to the ZA27 alloy can refine microstructure and improve the damping capacity, the best modification effect and the highest damping capacity can be obtained at 03%RE content. It is believed that the damping mechanism of ZA27 alloy is associated with the viscous sliding or slipping of grain boundaries and interfaces, and the more the grain boundaries and interfaces, the higher the damping capacity of ZA27 alloy can be obtained.展开更多
Equal channel angular extrusion (ECAE) was applied to commercial pure magnesium and AZ91D alloy. Microstructures of these magnesium alloys before and after ECAE process were observed by optical microscopy (OM). The ul...Equal channel angular extrusion (ECAE) was applied to commercial pure magnesium and AZ91D alloy. Microstructures of these magnesium alloys before and after ECAE process were observed by optical microscopy (OM). The ultimate tensile strength of pure magnesium and AZ91D alloy processed by ECAE is about 130 and 260MPa, respectively, and it is much higher than that of the as cast alloys. The elongation of them is increased from about 2% to 8%. The strain amplitude dependence damping capacities of these magnesium alloys were investigated by dynamic mechanical analyzer (DMA). ECAE process largely decreases the damping capacities of pure magnesium from 0.033 to about 0.012 (ε=1×10 -4), but does not show obvious influence on that of AZ91D alloy, which is about 0.0015.展开更多
ZA27 alloy was prepared by casting with permanent mold and then annealed at 250℃ for 1-4h. The damping capaciG of the alloy was measured using a testing apparatus based on the cantilever beam technique. It was found ...ZA27 alloy was prepared by casting with permanent mold and then annealed at 250℃ for 1-4h. The damping capaciG of the alloy was measured using a testing apparatus based on the cantilever beam technique. It was found that the as-cast ZA27 alloy possesses high damping capacity with the value of 1.3 × 10^4 at 320Hz. After annealed at 250℃ for lh, the damping capacity decreases to 1.1 × 10^-3 and then remains constant even when the annealing time is increased to 4h. The microstructure of the as-cast ZA27 alloy consists of large dendrites of Al-rich PrimaG (x-phases, eutectoid (α + η) and nonequilibrium eutectic phases (α + η + ε). After annealing at 250℃ for lh, the e phase disappears due to dissolution into the matrix, and the spacing between the flakes of eutectoid increases. The further increase in the annealing time has little effect on the spacing. The damping mechanism of the alloy was discussed considering the thermoelastic damping and defect damping. The value of thermoelastic damping accounts only for 7%-8% in the overall damping in cantilever beam damping measurements and the damping capacity of the ZA27 alloy came mainly from defect damping.展开更多
In this study,the optimization of mechanical and damping capacities of Mg-0.6 wt.%Zr alloys by controlling the recrystallized(DRXed)grain size under varying extrusion processing parameters including extrusion temperat...In this study,the optimization of mechanical and damping capacities of Mg-0.6 wt.%Zr alloys by controlling the recrystallized(DRXed)grain size under varying extrusion processing parameters including extrusion temperature T and strain rate was investigated.The relationship between the DRXed grain size and damping properties of the studied alloy was also discussed.The DRXed grain size of the as-extruded Mg-Zr alloys decreased as the extrusion temperature T decreased and the strain rateεincreased.As the DRXed grain size decreased,the strength and elongation of the as-extruded alloys exhibited improved performance through the grain refinement mechanism,while the damping properties deteriorated.The extrusion temperature of the Mg-Zr alloy had relatively greater effects on the mechanical and damping properties than the strain rate.The results of the present work indicate that alloys with appropriate mechanical and damping properties may be obtained from controlling the DRXed grain size by careful tailoring of the extrusion process parameters.展开更多
Zn-Al alloys constitute an interesting group of foundry alloys. Due to a relatively low melting temperature, they allow a decrease in energy-consumption of the melting process and alloy preparation. The vibration damp...Zn-Al alloys constitute an interesting group of foundry alloys. Due to a relatively low melting temperature, they allow a decrease in energy-consumption of the melting process and alloy preparation. The vibration damping ability is one of the most interesting properties of the Zn-Al alloys. Zn-Al alloys are divided into two groups: the low-aluminium and high-aluminium alloys. The investigated Zn-10 wt.% Al(ZnAl10) alloy is representative of the high-aluminium alloys, which, on account of its tendency of forming coarse-grained structures, has rather low plastic properties, including elongation. In order to improve the plastic properties, a modification treatment is usually applied. The dependence of the damping coefficient of the ultrasound wave on the amount of the introduced inoculant was studied. Investigations were performed using the AlT i3C0.15 inoculant as the modifier of the ZnAl10 alloy. It was found that titanium additions, in a range from 25 to 100 ppm in relation to the melted charge mass, can reduce the damping coefficient value. An increase of the inoculant addition causes a rise of the damping coefficient, which is probably related to the scattering of the ultrasound wave on Al_3Ti and TiC particles introduced with the inoculant.展开更多
High manganese steel has wide prospects in industry due to their excellent mechanical and damping properties. The quenching structures of high manganese steel are ε-martensite, γ-austenite and α'-martensite. Re...High manganese steel has wide prospects in industry due to their excellent mechanical and damping properties. The quenching structures of high manganese steel are ε-martensite, γ-austenite and α'-martensite. Researches show that the damping properties of high manganese steel are related to these microstructures. Besides, there are many ways to improve the damping property of damping alloys. This paper reviews the damping mechanism and the influences of the ad-dition of alloying elements, heat treatment, pre-deformation and other factors on their damping performance, hoping to provide methods and ideas for the study of damping properties of high manganese steel. .展开更多
Alloying is a good approach to increasing its strength but leads to a reduction of damping to pure magnesium.Classifying the alloying characteristics of various alloying elements in magnesium alloys and their combined...Alloying is a good approach to increasing its strength but leads to a reduction of damping to pure magnesium.Classifying the alloying characteristics of various alloying elements in magnesium alloys and their combined effects on the damping and mechanical properties of magnesium alloys is important.In this paper,the properties of the Mg-0.6wt%X binary alloys were analyzed through strength measurements and dynamic mechanical analysis.The effects of foreign atoms on solid-solution strengthening and dislocation damping were studied comprehensively.The effect of solid solubility on damping capacity can be considered from two perspectives:the effect of single solid-solution atoms on the damping capacities of the alloy,and the effect of solubility on the damping capacities of the alloy.The results provide significant information that is useful in developing high-strength,high-damping magnesium alloys.This study will provide scientific guidance regarding the development of new types of damping magnesium alloys.展开更多
The microstructures and damping capacity of AZ91D cast alloys containing various Ce contents were investigated. Damping capacity (Q-1) of the alloys was measured by cantilever beam technique, and the relationship betw...The microstructures and damping capacity of AZ91D cast alloys containing various Ce contents were investigated. Damping capacity (Q-1) of the alloys was measured by cantilever beam technique, and the relationship between damping capacity and strain amplitude was investigated. The results show that Al4Ce phase is formed in AZ91D alloy after adding a certain quantity of Ce contents, then as-cast microstructures of the alloys are refined. Meanwhile the damping capacity of the alloys is also improved. When the mass fraction of Ce is 0.7%, the most obvious refinement effect and the maximum damping capacity can be obtained. When the damping capacity (Q-1) is )2.728)×10-3, 61% increment can be obtained compared with unmodified AZ91D alloy. The damping capacity of the alloys is relative to strain amplitude, and the damping behavior can be explained by the theory of Granato and Lücke.展开更多
Optical microscope,X-ray diffractometer,scanning electron microscope,tensile tester and dynamic mechanical analyzer(DMA) were applied to investigate the effects of Y and Zn additions on microstructure,mechanical prope...Optical microscope,X-ray diffractometer,scanning electron microscope,tensile tester and dynamic mechanical analyzer(DMA) were applied to investigate the effects of Y and Zn additions on microstructure,mechanical properties and damping capacity of Mg-3Cu-1Mn(CM31) alloy.The results show that with the increase of Y and Zn contents,the secondary dendrite arm spacing of alloys is reduced;meanwhile,the yield strength is increased.In low strain amplitude,the damping capacity of alloys with Y and Zn addition is lower than that of CM31 alloy.However,in strain amplitude over 5×10-3,the damping capacity of alloy with a trace of Y and Zn addition(1%Y and 2%Zn,mass fraction) increases abnormally with the increase of strain amplitude and is near to that of pure Mg,probably due to the increase of dislocation density caused by the precipitation of secondary phase.The temperature dependence of damping capacity of above alloy was also tested and discussed.展开更多
Strain amplitude dependence of the logarithmic decrement was measured and studied on an AZ61 magnesium alloy at room temperature. Measurements were carried out before and after isochronal thermal treatment step by ste...Strain amplitude dependence of the logarithmic decrement was measured and studied on an AZ61 magnesium alloy at room temperature. Measurements were carried out before and after isochronal thermal treatment step by step with increasing temperature. For all specimens, the strain dependence of the logarithmic decrement exhibits two regions. At lower strains the logarithmic decrement is strain independent and in the higher strain region it depends strongly on strain amplitude. The strain-independent logarithmic decrement is mainly composed of thermoelastic damping and dislocation damping, which can be explained by Granato-Lücke theory. In addition, the strain-independent logarithmic decrement for the specimens annealed at higher temperatures is a little lower than that for as-cast specimen, and it increases with increasing temperature of heat treatment. Microstructure changes due to heat treatment are responsible for changes of the logarithmic decrement.展开更多
基金funded by the National Natural Science Foundation of China(Nos.51801189)The Central Guidance on Local Science and Technology Development Fund of Shanxi Province(Nos.YDZJTSX2021A027)+2 种基金The National Natural Science Foundation of China(Nos.51801189)The Science and Technology Major Project of Shanxi Province(No.20191102008,20191102007)The North University of China Youth Academic Leader Project(No.11045505).
文摘This work studied the microstructure,mechanical properties and damping properties of Mg_(95.34)Ni_(2)Y_(2.66) and Mg_(95.34)Zn_(1)Ni_(1)Y_(2.66)alloys systematically.The difference in the evolution of the long-period stacked ordered(LPSO)phase in the two alloys during heat treatment was the focus.The morphology of the as-cast Mg_(95.34)Ni_(2)Y_(2.66)presented a disordered network.After heat treatment at 773 K for 2 hours,the eutectic phase was integrated into the matrix,and the LPSO phase maintained the 18R structure.As Zn partially replaced Ni,the crystal grains became rounded in the cast alloy,and lamellar LPSO phases and more solid solution atoms were contained in the matrix after heat treatment of the Mg_(95.34)Zn_(1)Ni_(1)Y_(2.66)alloy.Both Zn and the heat treatment had a significant effect on damping.Obvious dislocation internal friction peaks and grain boundary internal friction peaks were found after temperature-dependent damping of the Mg_(95.34)Ni_(2)Y_(2.66)and Mg_(95.34)Zn_(1)Ni_(1)Y_(2.66)alloys.After heat treatment,the dislocation peak was significantly increased,especially in the alloy Mg_(95.34)Ni_(2)Y_(2).66.The annealed Mg_(95.34)Ni_(2)Y_(2.66)alloy with a rod-shaped LPSO phase exhibited a good damping performance of 0.14 atε=10^(−3),which was due to the difference between the second phase and solid solution atom content.These factors also affected the dynamic modulus of the alloy.The results of this study will help in further development of high-damping magnesium alloys.
基金financially supported by the National Key Research and Development Program of China(No.2021YFB 3701100)the National Natural Science Foundation of China(Nos.52171104 and U20A20234)+2 种基金the Chongqing Research Program of Basic Research and Frontier Technology,China(Nos.cstc2021ycjh-bgzxm0086 and 2019jcyj-msxmX0306)the Fundamental Research Funds for Central Universities,China(Nos.SKLMT-ZZKT-2022R04,2021CDJJMRH-001,and SKLMT-ZZKT-2022M12)the 111 Project by the Ministry of Education and the State Administration of Foreign Experts Affairs of China(No.B16007)。
文摘Optimizing the mechanical properties and damping capacity of the duplex-structured Mg–Li–Zn–Mn alloy by tailoring the microstructure via hot extrusion was investigated.The results show that the Mg–8Li–4Zn–1Mn alloy is mainly composed ofα-Mg,β-Li,Mg–Li–Zn and Mn phases.The microstructure of the test alloy is refined owing to dynamic recrystallization(DRX)during hot extrusion.After hot extrusion,the crushed precipitates are uniformly distributed in the test alloy.The yield strength(YS),ultimate tensile strength(UTS),and elongation(EL)of as-extruded alloy reach 156 MPa,208 MPa,and 32.3%,respectively,which are much better than that of as-cast alloy.Furthermore,the as-extruded and as-cast alloys both exhibit superior damping capacities,with the damping capacity(Q^(-1))of 0.030 and 0.033 at the strain amplitude of 2×10^(-3),respectively.The mechanical properties of the test alloy can be significantly improved by hot extrusion,whereas the damping capacities have no noticeable change,which indicates that the duplex-structured Mg–Li alloys with appropriate mechanical properties and damping properties can be obtained by alloying and hot extrusion.
文摘The damping behaviors of Zn-Al alloys with fully lamellar microstructures were simulated with the cell method. The influences of the grain boundary condition, the strain amplitude, the number of the lamellae in the grain (N) and the content ratio of Zn and Al in Zn-Al alloys on the damping capacity were investigated. The results indicate that the grain boundary condition has great influence on the damping capacity of Zn-Al alloys, and also affects the relationship between the damping capacity and the number of lamellae (N). The variation of damping capacity with the strain amplitude is increasing exponentially with the strain amplitude and the damping capacity increases with the increasing of content of Zn.
文摘The stress strain curves of two CuZnAl shape memory alloys which have the martensitic transformation temperatures of 50 ℃ and -10 ℃ respectively, were measured by using electronic material tester after treated by different heat-treatment conditions. The results show that the area enclosed by hysteresis loop of the CuZnAl shape memory alloy in martensitic state is much larger than that of the alloy in austenitic state with super-elasticity at room temperature. Therefore, the former has better vibration attenuation effect. After being oil-quenched, water-quenched, and step-quenched, the CuZnAl alloy takes on more stable shape memory effect,better super-plasticity and superelasticity (pseudoelasticity). A CuZnAl shape memory alloy damper was designed, produced and installed to a 2-layer frame structure. In addition, the vibration experiments were made by dynamic data collecting analysis meter. The velocity of vibration attenuation of frame structure with CuZnAl shape memory alloy damper is much faster than that without it. And with the help of CuZnAl shape memory alloy damper, the attenuation period reduces to 1/10 of the original.
基金financially supported by the National Natural Science Foundation of China (Nos. 51174060 and 51301109)the Science and Technology Department of Liaoning Province of China (No. 2013223004)the Fundamental Research Funds for the Central Universities (No. 140203004)
文摘The damping properties of an Mg alloy foam and its composite foams were investigated using a dynamic mechanical thermal analyzer. The results show that the loss factors of both the Mg alloy and its composite foams are insensitive to temperature and loading frequency when the temperature is less than a critical temperature Tcrit. However, it increases when the temperature exceeds the Tcrit values, which are 200 and 250°C for the Mg alloy foam and the Mg alloy/SiCp composite foams, respectively. The Mg alloy/SiCp composite foams exhibit a higher damping capacity than the Mg alloy foam when the temperature is below 200°C. By contrast, the Mg alloy foam exhibits a better damping capacity when the temperature exceeds 250°C. The variation in the damping capacity is attributed to differences in the internal friction sources, such as the characteristics of the matrix material, abundant interfaces, and interfacial slipping caused by SiC particles, as well as to macrodefects in the Mg alloy and its composite foams.
文摘This paper investigated high-damping Cu-Al-Be-B cast alloys using metallographic analysis, X-ray diffraction (XRD) and electrical resistance measurements for transformation temperatures. The results showed that beryllium can stabilize β phase, resulting in a thermo-elastic martensite microstructure leading to high-damping capacity in cast Cu-Al-Be-B alloys. Trace additions of boron to Cu-Al-Be alloys can significantly refine the grains, providing high strength and ductility to the alloys. A factorial design of experiment method was used to optimize the composition and properties of cast Cu-Al-Be-B alloys. The optimal microstructure for thermo-elastic martensite can be obtained by adjusting the amounts of aluminum and beryllium to eutectoid or pseudo-eutectoid compositions. An optimized cast Cu-Al-Be-B alloy was developed to provide excellent mechanical properties, tensile strength σ_b=767MPa, elongation δ=7.62%, and damping capacity S. D. C=18.70%.
基金supported by National Natural Science Foundation of China (Nos.50671083 and 50571081)Aeronautical Science Foundation of China (No.04G53042)Natural Science Foundation of the Shaanxi Province(No.2007E101)
文摘Microstructure observation and dynamic mechanical analysis were carried out to investigate the precipitation and responding damping behaviors of AZ31 magnesium alloy. All the strain amplitude-dependent damping curves of the aged alloys are located between the curves of solutionized and as-cast alloys, although they have different critical strain amplitudes. The G-L theory is employed to explain the damping mechanism involving the interaction between the dislocation and the precipitated phase. In addition, a damping peak is observed at temperatures close to 330 ℃ for AZ31 magnesium alloy, which is related to the β-MglTA112 phase dissolution.
文摘The modification mechanism and damping capacity(Q-1) of conventional ascast ZA27 alloy modified by Al10%RE were investigated. Cantilever beam technique was used to measure the damping capacity. The experimental results show that the addition of RE to the ZA27 alloy can refine microstructure and improve the damping capacity, the best modification effect and the highest damping capacity can be obtained at 03%RE content. It is believed that the damping mechanism of ZA27 alloy is associated with the viscous sliding or slipping of grain boundaries and interfaces, and the more the grain boundaries and interfaces, the higher the damping capacity of ZA27 alloy can be obtained.
文摘Equal channel angular extrusion (ECAE) was applied to commercial pure magnesium and AZ91D alloy. Microstructures of these magnesium alloys before and after ECAE process were observed by optical microscopy (OM). The ultimate tensile strength of pure magnesium and AZ91D alloy processed by ECAE is about 130 and 260MPa, respectively, and it is much higher than that of the as cast alloys. The elongation of them is increased from about 2% to 8%. The strain amplitude dependence damping capacities of these magnesium alloys were investigated by dynamic mechanical analyzer (DMA). ECAE process largely decreases the damping capacities of pure magnesium from 0.033 to about 0.012 (ε=1×10 -4), but does not show obvious influence on that of AZ91D alloy, which is about 0.0015.
基金This work was supported by the National Natural Science Foundation of China(No.50075068)Scientific Research Project of Department of Education of Shaanxi Province(No.03JK132)Natural Science Foundation of Shaanxi Province(No.2003E1 11).
文摘ZA27 alloy was prepared by casting with permanent mold and then annealed at 250℃ for 1-4h. The damping capaciG of the alloy was measured using a testing apparatus based on the cantilever beam technique. It was found that the as-cast ZA27 alloy possesses high damping capacity with the value of 1.3 × 10^4 at 320Hz. After annealed at 250℃ for lh, the damping capacity decreases to 1.1 × 10^-3 and then remains constant even when the annealing time is increased to 4h. The microstructure of the as-cast ZA27 alloy consists of large dendrites of Al-rich PrimaG (x-phases, eutectoid (α + η) and nonequilibrium eutectic phases (α + η + ε). After annealing at 250℃ for lh, the e phase disappears due to dissolution into the matrix, and the spacing between the flakes of eutectoid increases. The further increase in the annealing time has little effect on the spacing. The damping mechanism of the alloy was discussed considering the thermoelastic damping and defect damping. The value of thermoelastic damping accounts only for 7%-8% in the overall damping in cantilever beam damping measurements and the damping capacity of the ZA27 alloy came mainly from defect damping.
基金The authors are grateful for the financial support from the foundation support of the Key Laboratory of Science and Technology on High Energy Laser,CAEP,the National Natural Science Foundation Commission of China(Grant No.51271206)the National Basic Research Program of China(Grant No.2013CB632201)the Program for New Century Excellent Talents in University(Grant No.NCET-11-0554).
文摘In this study,the optimization of mechanical and damping capacities of Mg-0.6 wt.%Zr alloys by controlling the recrystallized(DRXed)grain size under varying extrusion processing parameters including extrusion temperature T and strain rate was investigated.The relationship between the DRXed grain size and damping properties of the studied alloy was also discussed.The DRXed grain size of the as-extruded Mg-Zr alloys decreased as the extrusion temperature T decreased and the strain rateεincreased.As the DRXed grain size decreased,the strength and elongation of the as-extruded alloys exhibited improved performance through the grain refinement mechanism,while the damping properties deteriorated.The extrusion temperature of the Mg-Zr alloy had relatively greater effects on the mechanical and damping properties than the strain rate.The results of the present work indicate that alloys with appropriate mechanical and damping properties may be obtained from controlling the DRXed grain size by careful tailoring of the extrusion process parameters.
基金financially supported by the resources of the National Science Centre of Poland awarded on the basis of the decision No.DEC-2011/01/N/ST8/07054
文摘Zn-Al alloys constitute an interesting group of foundry alloys. Due to a relatively low melting temperature, they allow a decrease in energy-consumption of the melting process and alloy preparation. The vibration damping ability is one of the most interesting properties of the Zn-Al alloys. Zn-Al alloys are divided into two groups: the low-aluminium and high-aluminium alloys. The investigated Zn-10 wt.% Al(ZnAl10) alloy is representative of the high-aluminium alloys, which, on account of its tendency of forming coarse-grained structures, has rather low plastic properties, including elongation. In order to improve the plastic properties, a modification treatment is usually applied. The dependence of the damping coefficient of the ultrasound wave on the amount of the introduced inoculant was studied. Investigations were performed using the AlT i3C0.15 inoculant as the modifier of the ZnAl10 alloy. It was found that titanium additions, in a range from 25 to 100 ppm in relation to the melted charge mass, can reduce the damping coefficient value. An increase of the inoculant addition causes a rise of the damping coefficient, which is probably related to the scattering of the ultrasound wave on Al_3Ti and TiC particles introduced with the inoculant.
文摘High manganese steel has wide prospects in industry due to their excellent mechanical and damping properties. The quenching structures of high manganese steel are ε-martensite, γ-austenite and α'-martensite. Researches show that the damping properties of high manganese steel are related to these microstructures. Besides, there are many ways to improve the damping property of damping alloys. This paper reviews the damping mechanism and the influences of the ad-dition of alloying elements, heat treatment, pre-deformation and other factors on their damping performance, hoping to provide methods and ideas for the study of damping properties of high manganese steel. .
基金financially supported by the National Natural Science Foundation of China(Nos.51361010 and 51665012)the Jiangxi Province Science Fund for Distinguished Young Scholars(Nos.20171BCB23061 and 2018ACB21020)
文摘Alloying is a good approach to increasing its strength but leads to a reduction of damping to pure magnesium.Classifying the alloying characteristics of various alloying elements in magnesium alloys and their combined effects on the damping and mechanical properties of magnesium alloys is important.In this paper,the properties of the Mg-0.6wt%X binary alloys were analyzed through strength measurements and dynamic mechanical analysis.The effects of foreign atoms on solid-solution strengthening and dislocation damping were studied comprehensively.The effect of solid solubility on damping capacity can be considered from two perspectives:the effect of single solid-solution atoms on the damping capacities of the alloy,and the effect of solubility on the damping capacities of the alloy.The results provide significant information that is useful in developing high-strength,high-damping magnesium alloys.This study will provide scientific guidance regarding the development of new types of damping magnesium alloys.
文摘The microstructures and damping capacity of AZ91D cast alloys containing various Ce contents were investigated. Damping capacity (Q-1) of the alloys was measured by cantilever beam technique, and the relationship between damping capacity and strain amplitude was investigated. The results show that Al4Ce phase is formed in AZ91D alloy after adding a certain quantity of Ce contents, then as-cast microstructures of the alloys are refined. Meanwhile the damping capacity of the alloys is also improved. When the mass fraction of Ce is 0.7%, the most obvious refinement effect and the maximum damping capacity can be obtained. When the damping capacity (Q-1) is )2.728)×10-3, 61% increment can be obtained compared with unmodified AZ91D alloy. The damping capacity of the alloys is relative to strain amplitude, and the damping behavior can be explained by the theory of Granato and Lücke.
基金Project(10876045) supported by the National Natural Science Foundation of China and China Academy of Engineering PhysicsProject(2007CB613704) supported by the National Basic Research Program of ChinaProject(CSTS2008AB4114) supported by Chongqing Science and Technology Commission,China
文摘Optical microscope,X-ray diffractometer,scanning electron microscope,tensile tester and dynamic mechanical analyzer(DMA) were applied to investigate the effects of Y and Zn additions on microstructure,mechanical properties and damping capacity of Mg-3Cu-1Mn(CM31) alloy.The results show that with the increase of Y and Zn contents,the secondary dendrite arm spacing of alloys is reduced;meanwhile,the yield strength is increased.In low strain amplitude,the damping capacity of alloys with Y and Zn addition is lower than that of CM31 alloy.However,in strain amplitude over 5×10-3,the damping capacity of alloy with a trace of Y and Zn addition(1%Y and 2%Zn,mass fraction) increases abnormally with the increase of strain amplitude and is near to that of pure Mg,probably due to the increase of dislocation density caused by the precipitation of secondary phase.The temperature dependence of damping capacity of above alloy was also tested and discussed.
文摘Strain amplitude dependence of the logarithmic decrement was measured and studied on an AZ61 magnesium alloy at room temperature. Measurements were carried out before and after isochronal thermal treatment step by step with increasing temperature. For all specimens, the strain dependence of the logarithmic decrement exhibits two regions. At lower strains the logarithmic decrement is strain independent and in the higher strain region it depends strongly on strain amplitude. The strain-independent logarithmic decrement is mainly composed of thermoelastic damping and dislocation damping, which can be explained by Granato-Lücke theory. In addition, the strain-independent logarithmic decrement for the specimens annealed at higher temperatures is a little lower than that for as-cast specimen, and it increases with increasing temperature of heat treatment. Microstructure changes due to heat treatment are responsible for changes of the logarithmic decrement.