Effect of annealing temperature on microstructure and mechanical properties of Mg-Zn-Zr-Nd alloy with large final rolling deformation

In this study,the Mg-3Zn-0.5Zr-χNd(χ=0,0.6)alloys were subjected to final rolling treatment with large deformation of 50%.The impact of annealing temperatures on the microstructure and mechanical properties was investigated.The rolled Mg-3Zn-0.5Zr-0.6Nd alloy exhibited an ultimate tensile strength of 386 MPa,a yield strength of 361 MPa,and an elongation of 7.1%.Annealing at different temperatures resulted in reduced strength and obviously increased elongation for both alloys.Optimal mechanical properties for the Mg-3Zn-0.5Zr-0.6Nd alloy were achieved after annealing at 200℃,with an ultimate tensile strength of 287 MPa,a yield strength of 235 MPa,and an elongation of 26.1%.The numerous deformed microstructures,twins,and precipitated phases in the rolled alloy could impede the deformation at room temperature and increase the work hardening rate.After annealing,a decrease in the work hardening effect and an increase in the dynamic recovery effect were obtained due to the formation of fine equiaxed grains,and the increased volume fraction of precipitated phases,which significantly improved the elongation of the alloy.Additionally,the addition of Nd element could enhance the annealing recrystallization rate,reduce the Schmid factor difference between basal and prismatic slip systems,facilitate multi-system slip initiation and improve the alloy plasticity.

Effect of yttrium on microstructures and mechanical properties of hot rolled AZ61 wrought magnesium alloy

The microstructures and mechanical properties of the rolled AZ61 alloys containing different contents of Y (0, 0.5, 0.9, 1.4%Y respectively) were studied. Phase analysis was performed by X-ray diffraction(XRD). Microstructures of experimental materials were observed by optical microscope(OM) and scanning electron microscope(SEM) equipped with energy dispersive spectrometer(EDS). The results show that the alloys with variable Y contents all contain a second-phase Al2Y. The amount of Al2Y increases with the increasing of Y content while that of Mg17Al12 decreases. Moreover, Y refines the microstructures of as-cast and rolled alloys. The finest average grain size is obtained in the alloy containing 0.9%Y with the best mechanical properties. When the Y content is up to 1.4%, Al2Y phase in the alloy coarsens, which leads to the drop of tensile strength.

Influence of texture and microstructure on mechanical properties of high-strength wrought magnesium alloy AZ80

Monotonic (tensile and compressive) and high cycle fatigue properties of the forged magnesium alloy AZ80 were investigated by using specimens with load axis parallel to longitude (L) or transverse (T) direction. A pronounced directional anisotropy in monotonic tests was observed in AZ80, i.e. the yield stress in T-direction is significantly lower than that in L direction. However, the directional anisotropy is absent in fatigue, fatigue strengths in both L- and T-directions are essentially equal. The absence of directional anisotropy in fatigue is possibly associated with the microstructure of AZ80. A homogeneous single phase structure probably alleviates the directional anisotropy of fatigue properties of the wrought magnesium alloy.

Effect of hot rolling on microstructure and properties of the ZEK100 alloy

Attempts to expand manufacturing capabilities of magnesium-based sheet materials are described.The as-cast ZEK100(Mg-1.2Zn-0.35Zr-0.17Nd,in wt%)magnesium alloy was subjected to hot rolling at temperatures from 350℃to 450℃using the laboratory 50 ton reversible mill with preheated rolls to manufacture the 1.5-1.7 mm thick sheet.The rolling temperature affected the sheet properties and an increase in the rolling temperature from 250 to 450℃caused reduction of tensile strength from 257 to 228 MPa ac-companied by a reduction in tensile yield stress from 237 to 185 MPa.At the same time,the alloy elongation increased from 17 to 21%.For the same rolling temperature range,the compressive strength reduced from 418 to 351 MPa.The post-rolling annealing at 450℃led to reduction of both tensile and compressive properties with the largest changes corresponding to the rolling temperature of 350°C.The correlation between the alloy grain size after rolling and the sheet properties was established where a reduction in grain size was accompanied by an increase of both the tensile/compressive strength and yield stress.Based on Hall-Petch relationship and an average grain size the correlation developed in this study may be used as the prediction model for properties of the hot rolled magnesium sheet.The results are discussed in terms of recent developments in magnesium sheet alloys and the vital role played in this process by rare earth elements.

Effect of rolling geometry on the mechanical properties, microstructure and recrystallization texture of Al–Mg–Si alloys

The effect of rolling geometry on mechanical properties, microstructure, and recrystallization texture of Al-Mg-Si alloys was studied by means of tensile tests, microstrucmral observations, and electron backscatter diffraction measurements. The results reveal that the elongation and the average plasticity strain ratio （r） values of the T4P （pre-aging plus natural aging）-treated alloy sheet with a rolling geome- try value between 1 and 3 are somewhat higher than those of the T4P-treated sheet with a rolling geometry value between 3 and 6. The deformation and recrystallization microstructures of the sheet with a rolling geometry value between 1 and 3 are more uniform than those of the sheet with a rolling geometry value between 3 and 6. The former also possesses somewhat higher surface quality. H {001 } 〈110〉 and Goss {110}〈001〉 orientations are the main recrystallization texture components for the former case, whereas the latter case only includes H {001 } 〈 110〉 orientation. Texture gradients are present in the two alloy sheets. Shear texture component F on the surface of the sheet with a rolling geometry value between 3 and 6 and its higher texture gradients have revealed that non-uniform deformation occurred during cold rolling. The effects of texture on the yield strength and r value were also discussed.

Effect of Ce on microstructure and mechanical properties of Mg-Zn-Ce magnesium alloys

The Mg-6Zn alloy with different contents of Ce was prepared by the gravity casting method,and then the Mg-6Zn-xCe(x=0,0.5,1.0,1.5,wt.%)alloys were extruded at 300℃and 350℃ after solution treatment.The phase constitution and microstructure evolution of Mg-Zn-xCe alloys were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and electron backscattering diffraction(EBSD).Meanwhile,the mechanical properties of the alloy were tested at room temperature.For as-cast alloys,the results show that the main compound in Mg-6Zn alloy is Mg4Zn7 phase,and the main compound is T-(MgZn)12Ce phase after the addition of different amounts of Ce.The microstructure and distribution of second phases are greatly improved after extrusion at 300℃and 350℃.Compared with initial mechanical properties,the strength and elongation increase obviously by means of extrusion at different temperatures.In addition,the microstructure after extrusion at 350℃is further analyzed according to EBSD data.The results show that rare earth element Ce probably promotes the activation of non-basal slip during the deformation process with the increase of Ce,which reduces the strength of basal texture and thus improves the plasticity of the alloy.Meanwhile,the increase of grain boundary migration ability leads to the gradual increase of recrystallization grain size and decreases the strength.

Study on anisotropy of microstructure and mechanical properties of AZ31 magnesium alloy fabricated by wire arc additive manufacturing

Based on wire arc additive manufacturing(WAAM)technology,AZ31 magnesium alloy in bulk was successfully fabricated,and its microstructure as well as mechanical properties in different planes were observed and analyzed.The AZ31 magnesium alloy has a similar microstructure in the building direction(Z)and travel direction(X),both of which are equiaxed grains.There are heat-affected zones(HAZs)with coarse grains below the fusion line.The second phase is primarily composed of the Mg17Al12 phase,which is evenly distributed in different directions.In addition,the residual stress varies in different directions.There is no significant difference in the hardness of the AZ31 alloy along the Z and X directions,with the average hardness being 68.4 HV and 67.9 HV,respectively.Even though the specimens’ultimate tensile strength along the travel direction is higher in comparison to that along the building direction,their differences in elongation and yield strength are smaller,indicating that the anisotropy of the mechanical properties of the material is small.

Influence of rolling directions on microstructure,mechanical properties and anisotropy of Mg-5Li-1Al-0.5Y alloy

Mg-5Li-1Al-0.5Y alloy was rolled with different directions.The microstructure,mechanical properties and texture of the specimens were investigated with optical microscope,tensile tester and X-ray diffraction.The results show that changing rolling directions can refine the grain size of as-rolled alloys.Meanwhile,rolling directions have an obvious influence on the mechanical properties and texture of Mg-5Li-1Al-0.5Y alloy,thus affecting the anisotropy of the alloy.The sheet,of which the RD(rolling direction)and ND(normal direction)are both changed between two passes,possesses the smallest anisotropy.From the texture results,changing rolling directions reduces the maximum pole density,making the highest point distribution region excursion and the highest point distributes more scatteredly.

Effect of rolling process on microstructures and mechanical properties of AZ31B alloy sheets

AZ31B magnesium extruded slabs prepared from LFEC were rolled at fairly lower temperature at 3, 6 and 16m/min rolling speeds into 1 mm thickness. The results indicate that the microstructures achieved by rolling at low temperature or at low rolling speed are composed of many prismatic regions divided by shear strips due to pile-up of twin crystals; the prismatic regions increase at elevated rolling temperature or at high rolling speed, and finally all are composed of equiaxed crystals without twin crystals due to dynamic recrystallization. After optimizing control of rolling process, excellent mechanical properties would be acquired. The mechanical properties of AZ31B sheet areρb=350 MPa,ρ0.2=300 MPa, andδ=12.0% when rolled at 6 m/min. At the same time, the difference of mechanical properties between transverse and longitudinal direction reduced markedly.

Microstructure and Mechanical Properties of AZ31 Alloys Processed by Residual Heat Rolling

To produce high strength and ductility Mg alloys with high productivity and low energy consumption,the residual heat rolling (RHR) process was initially proposed.The microstucture and mechanical properties of AZ31 processed by RHR were investigated by optical micrscopy (OM),electron backscatter diffraction (EBSD),and electron universal testing machine.The yield strength (YS),ultimate tensile strength (UTS),and elongation to failure of RHRed AZ31 sheet were 194 MPa,311 MPa,and 22%,respectively.The RHRed AZ31 alloys after annealing have very fine and homogeneous grains.The symmetrical rolled (SR) and RHRed AZ31 exhibit typical {0002} basal textures.The RHRed AZ31 has double-peak basal texture distribution.The basal poles of RHRed AZ31 split from normal direction (ND) to rolling direction (RD).There are few hard orientation distributions on the basal slip and more soft orientation distributions on the prismatic slip in the RHRed AZ31 sheets than those in the SRed AZ31sheets.

Mechanical properties and texture evolution during hot rolling of AZ31 magnesium alloy

Mechanical properties and texture evolutions of the as-rolled AZ31 Mg sheets were investigated.The results show that the grains of the sheets are significantly refined after hot rolling.The mechanical properties of the as-rolled samples are enhanced due to the grain size refinement.The intensity of basal texture decreases with the increase of deformation ratio,and double-peak type basal texture is discovered in the intermediate and large strain hot rolling processes.The formation of the texture is ascribed to the activities of prismatic and non-basalslips,which is the same as the 30%rolled and 50%rolled samples.The incline of basal planes exerts an effect on the mechanical anisotropy during tension along rolling direction(RD)and transverse direction(TD)at room temperature.

Microstructure, cold rolling, heat treatment, and mechanical properties of Mg-Li alloys

The magnesium-lithium （Mg-Li） alloy exhibits two phase structures between 5.7wt% and 10.3wt% Li contents, consisting of the a （hcp） Mg-rich and the β （bcc） Li-rich phases, at room temperature. In the experiment, Mg-5Li-2Zn, Mg-9Li-2Zn, Mg-16Li-2Zn, Mg-22Li-2Zn, Mg-5Li-2Zn-2Ca, Mg-9Li-2Zn-2Ca, Mg-16Li-2Zn-2Ca, and Mg-22Li-2Zn-2Ca （wt%） were melted. During the melting process, the flux, which was composed of lithium chloride （LiCl） and lithium fluoride （LiF） in the proportion of 3：1 （mass ratio） and argon gas were used to protect the alloys from oxidation. The microstructure, mechanical properties, and cold-rolling workability of the wrought alloys were studied. The crystal grain of the alloys （adding Ga） is fine . The hardness of the studied alloys decreases with an increase in element Li. The density of the studied alloys is in the range of 1.187 to 1.617 g/cm^3. The reduction of the Mg-16Li-2Zn and Mg-22Li-2Zn alloys can exceed 85% at room temperature. The Mg-9Li-2Zn-2Ca alloy was heat treated at 300℃ for 8, 12, 16, and 24 h, respectively. The optimum heat treatment of the Mg-9Li-2Zn-2Ca alloy is 300℃×12h by metallographic observation and by studying the mechanical properties of the alloys.

Microstructure and properties of A2017 alloy strips processed by a novel process by combining semisolid rolling,deep rolling,and heat treatment

A novel short process for producing A2017 alloy strips with notable features of near net shape, saving energy, low cost, and high product performance was developed by combining semisolid rolling, deep rolling, and heat treatment. The microstructure and properties of the A2017 alloy strips were investigated by metallographic microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, tensile testing, and hardness measurement. The cross-sectional microstructure of the A2017 alloy strips is mainly composed of near-spherical primary grains. Many eutectic phases CuA12 formed along primary grain boundaries during semisolid rolling are crushed and broken into small particles. After solution treatment at 495℃ for 2 h the eutectic phases at grain boundaries have almost dissolved into the matrix. When the solution treatment time exceeds 2 h, grain coarsening happens. More and more grain interior phases precipitate with the aging time prolonging to 8 h. The precipitated particles are very small and distribute homogenously, and the tensile strength reaches its peak value. When the aging time is prolonged to 12 h, there is no obvious variation in the amount of precipitated phases, but the size and spacing of precipitated phases increase. The tensile strength of the A2017 alloy strips produced by the present method can reach 362.78 MPa, which is higher than that of the strips in the national standard of China.

Optimization on microstructure,mechanical properties and damping capacities of duplex structured Mg–8Li–4Zn–1Mn alloys

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.

Mechanism of Effects of Rare Earths on Microstructure and Properties at Elevated Temperatures of AZ91 Magnesium Alloy

By using real-space recursion method,the energetics of the undoped and Al and/or RE atoms doped 7（1450）〈0001〉 symmetric tilt grain boundaries（GBs）in AZ91 alloys were investigated.Similar calculations were performed on undoped and doped bulk α Mg for comparison.The results showed that Al atoms segregated at GBs in AZ91 alloys.When RE atoms were added,they also segregated at GBs,and their segregation is stronger than Al atoms＇.Therefore,RE atoms retard the segregation of Al atoms.Calculations of interaction energy indicated that Al atoms repelled each other,and could form ordered phase with host Mg atoms.On the contrary to the case of Al,RE atoms attracted each other,they could not form ordered phase with Mg,but could form clusters.Between RE and Al,there existed attractive interaction,and this attractive interaction was the origin of Al11RE3 precipitation.Precipitation of Al11RE3 particles with high melting point and high thermal stability along GB improves high temperature properties of AZ91 alloys.

Effect of Yttrium and Cerium Addition on Microstructure and Mechanical Properties of AM50 Magnesium Alloy

To develop magnesium alloy with low cost, high strength and excellent elevated temperature properties, effect of Y and Ce addition on microstructure and mechanical properties of AM50 magnesium alloy was studied. Result showed that addition of small amount of Y and Ce to AM50 alloys resulted in refinement of microstructure. Owing to the improvement of microstructure, the mechanical properties of alloys at both ambient and elevated temperature were increased. AM50 alloy containing 0.6 % Ce-0.3 % Y （mass fraction） had good refinement effect and relatively ideal mechanical properties.

Effects of RE on Microstructures and Mechanical Properties of Hot-Extruded AZ31 Magnesium Alloy

Effects of rare earth (RE) additions on microstructure and mechanical properties of the wrought AZ31 magnesium alloy were investigated. The results show that, by adding 0.3%, 0.6% and 1.0% RE elements, the as-cast microstructure can be refined, and the as-cast alloys′ elongation and tensile strength can be improved. After extrusion, the alloy with 0.3% and 0.6% RE additions obtain a finer microstructure and the best mechanical properties, but the alloy with 1.0% RE addition has the coarse Al-RE compound particles in grain boundaries which decreased elongation and tensile properties. Usually, Rare earth (RE) elements were used to improve the creep properties of aluminium-containing magnesium pressure die cast alloys at elevated temperatures. In this paper, it is also found that the high temperature strength of extruded materials can be increased by RE elements additions.

Effects of Er on the microstructure and properties of AZ31 magnesium alloy prepared via the EMS process

The effects of small amounts of the rare-earth element erbium on the microstructure and the mechanical properties of AZ31 magnesium alloy via the electromagnetic stirring （EMS） process have been studied. It has been shown that AZ31-Er alloys are mainly composed of α-Mg solid solution and β-Mg17TA112 phases. When the Er content reaches 0.12 wt.%, the characteristic peaks of A12Er can be observed. The micro- structure is obviously refined and the tensile strength of the AZ31-based alloy at ambient temperature is significantly improved by contents of 0.03 wt.% Er, especially the elongation （8= 19%）. More addition of Er obviously decreases the tensile strength and elongation of the AZ31-based alloy because of the grain coarsening and the reduction of β-Mg17A112 phases.

Effect of pre-deformation on microstructure and mechanical properties of WE43 magnesium alloy II: Aging at 250 and 300℃

In this work,the microstructural evolution and mechanical properties of a pre-deformed WE43 magnesium alloy when aged at 250 and 300℃ were further investigated.It is found that the abundant deformation twins introduced by pre-deformation were maintained within the alloy during the aging treatment.Second particles formed at the twin boundaries and coarsened with aging time,especially at 300℃.When peak-aged at 250℃,the fine metastable β'''and β' precipitates formed in the un-deformed alloy have been transformed into relatively large β1 and β precipitates by the pre-deformation.While peak-aged at 300℃,the pre-deformation obviously refined the β precipitates.Mechanical properties indicate that pre-deformation can increase the yield strength by 19MPa and 54MPa for the peak-aged alloy at 250℃ and 300℃,respectively,and will not obviously deteriorate the tensile elongations.

Effect of Neodymium on As-Cast Microstructure and Mechanical Properties of AZ31 Wrought Alloy

Nd in the form of powder or intermediate alloy was added to AZ31 wrought alloy. The as-obtained alloy was characterized and tested with respect to its microstructure and mechanical properties. The relationship between the microstructure,mechanical properties and tensile fracture mechanism were discussed, with relevant alloys as reference for comparison. Experimental results show that the same quantity of Nd was added into AZ31 in powder form or in intermediate alloy, the absorption rate of Nd reached only 10.8% for the former case and as high as 95% for the later case. Pure Nd powder was added, no new compound was detected, but it served as reductant and purified alloy melt, resulting in improving the tensile strength while Nd was added into AZ31 as Mg-Nd intermediate alloy. The compound Al2Nd and Mg12Nd were formed in magnesium alloy, which were distributed in the matrix in the shapes of strip and particle, evidently refined the as-cast structure. The as-cast tensile strength (228 MPa) of adding pure Nd powder approximated to the figure (245 MPa) of adding Mg-Nd intermediate alloy. The tensile fracture mechanism of as-cast AZ31 transformed from cleavage fracture into quasi-cleavage fracture.