To indirectly investigate the dislocation behavior of Fe-36wt%Ni Invar alloy by the etch pit method, polished Invar specimens were etched by a solution containing 4 g copper sulfate, 20 mL hydrochloric acid, and 20 mL...To indirectly investigate the dislocation behavior of Fe-36wt%Ni Invar alloy by the etch pit method, polished Invar specimens were etched by a solution containing 4 g copper sulfate, 20 mL hydrochloric acid, and 20 mL deionized water for 2 min. Etch pits in the etched surfaces were observed. All the etch pits in one specific grain exhibited similar shapes, which are closely related to the grain orienta-tions. These etch pits were characterized as dislocation etch pits. It was observed that etch pits arranged along grain boundaries, gathered at grain tips and strip-like etch pit clusters passed through a number of grains in the pure Invar specimens. After the addition of a small amount of alloying elements, the identification of a single dislocation etch pit is challenging compared with the pure Invar alloy. Thus, the observation of etch pits facilitates the investigation on the dislocation behavior of the pure Invar alloy. In addition, alloying elements may affect the densities and sizes of etch pits.展开更多
Quantitative research on the heat affected zone ( HAZ) o f weave bead welding ( WBW) joint fo r Invar alloy is carried out in this paper. Based on the morphology and related data analysis of the weld se...Quantitative research on the heat affected zone ( HAZ) o f weave bead welding ( WBW) joint fo r Invar alloy is carried out in this paper. Based on the morphology and related data analysis of the weld seam, the width difference o f each layer and the forming mechanism are analyzed. Results show that the bottom layer ( Layer 1 ) has the widest HAZ and the smallest fluctuation, which reaches 1 200 |jLm. HAZ width o f layer 2 to 5 is relatively narrower which is basically below 600 jjim, while the amplitude fluctuation is greater. The main reason lies in the welding path. The long straight welding without weave causes the base metal near the groove fully melts which causes by the long straight welding without weave, while welding with weave leads to the uneven and inadequate melting of metal near groove.展开更多
The hot ductility of Fe-36Ni invar alloy with different additions of the element cerium was investigated using a Gleeble-3800 thermal-mechanical simulator over the temperature range 850 - 1 050℃, and the improvement ...The hot ductility of Fe-36Ni invar alloy with different additions of the element cerium was investigated using a Gleeble-3800 thermal-mechanical simulator over the temperature range 850 - 1 050℃, and the improvement mechanism of the hot ductility was analyzed using a combination of SEM, EDS, and OM. The results indicated that Fe-36Ni invar alloy exhibited poor hot ductility below 1 050℃, which was mainly attributed to weak grain boundaries and the action of grain boundary sliding. However, the alloys with cerium contents of 0. 016% and 0.024% both demonstrated substantial improvement in the hot ductility over the entire testing temperature range. The observed improvement of the hot ductility of the alloy with 0. 016% cerium at 950 ~C and the alloy with 0.024% cerium at 900℃ was associated mainly with the grain boundary strengthening and the restriction of the grain boundary sliding because the addition of cerium reduced the segregation of sulfur at grain boundaries and refined the grain structure. The occurrence and acceleration of dynamic recrystallization were found to be responsible for the high hot ductility of the alloy with 0.016% cerium at 1 000℃ and the alloy with 0. 024% cerium at 950 - 1 000℃ as a result of the refinement of the grain structure by addition of cerium.展开更多
The effect of Ce, La and mischmetal on the solidification structure of Fe-36Ni invar alloy was investigated. The results show that great amounts of high-melting point compounds ( Ce2O3, La202S and ( Ce, La)2O2S ) ...The effect of Ce, La and mischmetal on the solidification structure of Fe-36Ni invar alloy was investigated. The results show that great amounts of high-melting point compounds ( Ce2O3, La202S and ( Ce, La)2O2S ) respectively formed in the alloy with the addition of Ce, La or mischmetal. Based on the theory of lattice misfit, the lattice misfit between the (0001) surfaces of Ce2O3,Ce2O2S and La2O2S and (100) surface of Fe-36Ni invar alloy were 6.21%, 5.77 % and 5.42 %, respectively, which are relatively low. Therefore, Ce2 O3, La2 O2 S and ( Ce, La) 2 O2 S could serve as the core of heterogeneous nucleation, improve the equiaxed grain ratio, reduce the equiaxed grain size and refine the solidification structure of alloy.展开更多
The Fe-Ni36 alloy was prepared via the one-step electrolysis of a mixed oxides precursor in a molten Na2CO3-K2CO3 eutectic melt at 750℃,where porous Fe_(2)O_(3)-NiO pellets served as the cathode and the Ni10 Cu11 Fe ...The Fe-Ni36 alloy was prepared via the one-step electrolysis of a mixed oxides precursor in a molten Na2CO3-K2CO3 eutectic melt at 750℃,where porous Fe_(2)O_(3)-NiO pellets served as the cathode and the Ni10 Cu11 Fe alloy was an inert anode.During the electrolysis,Ni O was preferentially electro-reduced to Ni,then Fe_(2)O_(3)was reduced and simultaneously alloyed with nickel to form the Fe-Ni36 alloy.Different cell voltages were applied to optimize the electrolytic conditions,and a relatively low energy consumption of 2.48 k W·h·kg^(-1) for production of Fe Ni36 alloy was achieved under 1.9 V with a high current efficiency of 94.6%.The particle size of the alloy was found to be much smaller than that of the individual metal.This process provides a low-carbon technology for preparing the Fe-Ni36 alloy via molten carbonates electrolysis.展开更多
Effects of Ti-Ce refiners on the solidification structure and the hot ductility of Fe-36Ni invar alloy were investigated, the corresponding mechanisms were also discussed. The results showed that the solidification of...Effects of Ti-Ce refiners on the solidification structure and the hot ductility of Fe-36Ni invar alloy were investigated, the corresponding mechanisms were also discussed. The results showed that the solidification of the alloy was remarkably refined with the addition of 0.05%Ti-0.01%Ce refiners. Not only did the columnar grains become shorter and thinner, but the growth pattern of them changed into staggered growth from linear growth. The alloy had a bad hot ductility below 1050 °C, which was mainly attrib-uted to weaker boundaries and the presence of grain boundary sliding. However, the hot ductility of the alloy was highly enhanced at 850-1000 °C as the addition of 0.05%Ti-0.01%Ce refiners could refine grain sizes, thus hinder grain boundary sliding, strengthen the grain boundary and promote the grain boundary movement. The alloy had a good hot ductility over 1050 °C, dynamic recrys-tallization occurred and was found to be responsible for the better hot ductility. In addition, the average coefficient of thermal ex-pansion of the alloy decreased a little with the addition of 0.05%Ti-0.01%Ce refiners, which met the requirement of material prop-erties.展开更多
Invar alloy consisting of 64% iron and 36% nickel has been widely used for the production of shadow masks for organic light emitting diodes(OLEDs) because of its low thermal expansion coefficient(1.86 × 10^-6c...Invar alloy consisting of 64% iron and 36% nickel has been widely used for the production of shadow masks for organic light emitting diodes(OLEDs) because of its low thermal expansion coefficient(1.86 × 10^-6cm/°C).To fabricate micro-hole arrays on 30 lm invar alloy film,through-mask electrochemical micromachining(TMEMM) was developed and combined with a portion of the photolithography etching process.For precise hole shapes,patterned photoresist(PR) film was applied as an insulating mask.To investigate the relationship between the current density and the material removal rate,the principle of the electrochemical machining was studied with a focus on the equation.The finite element method(FEM) was used to verify the influence of each parameter on the current density on the invar alloy film surface.The parameters considered were the thickness of the PR mask,inter-electrode gap(IEG),and electrolyte concentration.Design of experiments(DOE) was used to figure out the contribution of each parameter.A simulation was conducted with varying parameters to figure out their relationships with the current density.Optimization was conducted to select the suitable conditions.An experiment was carried out to verify the simulation results.It was possible to fabricate micro-hole arrays on invar alloy film using TMEMM,which is a promising method that can be applied to fabrications of OLEDs shadow masks.展开更多
Measurements of magnetic susceptibility in mechanically alloyed Fe-Ni Invar alloys were taken under pressures up to 7.5GPa. The rate of decrease in the Curie temperature for 700℃ annealed specimen was larger than tha...Measurements of magnetic susceptibility in mechanically alloyed Fe-Ni Invar alloys were taken under pressures up to 7.5GPa. The rate of decrease in the Curie temperature for 700℃ annealed specimen was larger than that annealed at 1000℃. This result can be explained by considering the fact that the width of the concentration fluctuation becomes larger in the specimen annealed at lower temperature.展开更多
In this work,the Invar 36 alloys were manufactured using cold spray(CS)additive manufacturing technique.The systematic investigations were made on the microstructural evolution,thermal expansion and mechanical propert...In this work,the Invar 36 alloys were manufactured using cold spray(CS)additive manufacturing technique.The systematic investigations were made on the microstructural evolution,thermal expansion and mechanical properties under as-sprayed(AS)and heat-treated(HT)conditions.XRD(X-ray diffraction)and ICP-AES(inductively coupled plasma atomic emission spectroscopy)analyses show that no phase transformation,oxidation,nor element content change have occurred.The X-ray computed tomography(XCT)exhibited a near fully dense structure with a porosity of 0.025%in the helium-produced sample under as-sprayed condition,whereas the nitrogen-produced samples produced at 5 MPa and 800℃show more irregular pore defects.He-AS sample shows a more prominent grain refinement than that of nitrogen samples due to the more extensive plastic deformation.The post heat-treatment exhibited a promoted grain growth,inter-particle diffusion,as well as the formation of annealing twins.Between25℃and 200℃,the nitrogen samples possessed lower CTE(coefficient of thermal expansion)values(1.53×10^(-6)/℃)compared with those produced by casting and laser additive manufacturing.The He-AS samples exhibited a noticeable negative CTE value between 25℃and 200℃,which may due to the significant compressive residual stress(-272 MPa)compensating its displacement with temperature increase during CTE test.The N2-HT and He-HT Invar 36 samples present a notable balance between strength and ductility.In conclusion,the CS technique can be considered as a potential method to produce the Invar36 component with high thermal and mechanical performance.展开更多
Porous Si3N4 was brazed to Invar alloy in this study, and Ag-Cu-Ti/Cu/Ag-Cu multi-layered filler was designed to inhibit the formation of Fe2Ti and Ni3Ti intermetallic compounds. The effects of the brazing temperature...Porous Si3N4 was brazed to Invar alloy in this study, and Ag-Cu-Ti/Cu/Ag-Cu multi-layered filler was designed to inhibit the formation of Fe2Ti and Ni3Ti intermetallic compounds. The effects of the brazing temperature and the thickness of Cu interlayer on the microstructure and mechanical properties of brazed joints were investigated. The typical microstructure of the joint brazed with multi-layered filler was porous Si3N4/TiN + Ti5Si3/Ag-Cu eutectic[Cu[Ag-Cu eutectic/Cu-rich layer + diffusion layer/Invar. When the brazing temperature increased, the reaction layer at the ceramic/filler interface grew thicker and the Cu interlayer turned thinner. As the thickness of Cu interlayer increased from 50 to 150 μm, the joint strength first increased and then decreased. In this research, the maximum shear strength (73 MPa) was obtained when being brazed at 1173 K with a 100 μm Cu interlayer applied in the filler, which was 55% higher than that brazed with single Ag-Cu-Ti brazing alloy and had reached 86% of the ceramic. The release of residual stress and the barrier effect of Cu interlayer to inhibit the formation of Fe2Ti and Ni3Ti intermetallics played the major role in the improvement of joint strength.展开更多
文摘To indirectly investigate the dislocation behavior of Fe-36wt%Ni Invar alloy by the etch pit method, polished Invar specimens were etched by a solution containing 4 g copper sulfate, 20 mL hydrochloric acid, and 20 mL deionized water for 2 min. Etch pits in the etched surfaces were observed. All the etch pits in one specific grain exhibited similar shapes, which are closely related to the grain orienta-tions. These etch pits were characterized as dislocation etch pits. It was observed that etch pits arranged along grain boundaries, gathered at grain tips and strip-like etch pit clusters passed through a number of grains in the pure Invar specimens. After the addition of a small amount of alloying elements, the identification of a single dislocation etch pit is challenging compared with the pure Invar alloy. Thus, the observation of etch pits facilitates the investigation on the dislocation behavior of the pure Invar alloy. In addition, alloying elements may affect the densities and sizes of etch pits.
基金the financial support of the project from Shanghai Municipal Commission of Economy and Informatization (15XI-1-15)Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Quantitative research on the heat affected zone ( HAZ) o f weave bead welding ( WBW) joint fo r Invar alloy is carried out in this paper. Based on the morphology and related data analysis of the weld seam, the width difference o f each layer and the forming mechanism are analyzed. Results show that the bottom layer ( Layer 1 ) has the widest HAZ and the smallest fluctuation, which reaches 1 200 |jLm. HAZ width o f layer 2 to 5 is relatively narrower which is basically below 600 jjim, while the amplitude fluctuation is greater. The main reason lies in the welding path. The long straight welding without weave causes the base metal near the groove fully melts which causes by the long straight welding without weave, while welding with weave leads to the uneven and inadequate melting of metal near groove.
文摘The hot ductility of Fe-36Ni invar alloy with different additions of the element cerium was investigated using a Gleeble-3800 thermal-mechanical simulator over the temperature range 850 - 1 050℃, and the improvement mechanism of the hot ductility was analyzed using a combination of SEM, EDS, and OM. The results indicated that Fe-36Ni invar alloy exhibited poor hot ductility below 1 050℃, which was mainly attributed to weak grain boundaries and the action of grain boundary sliding. However, the alloys with cerium contents of 0. 016% and 0.024% both demonstrated substantial improvement in the hot ductility over the entire testing temperature range. The observed improvement of the hot ductility of the alloy with 0. 016% cerium at 950 ~C and the alloy with 0.024% cerium at 900℃ was associated mainly with the grain boundary strengthening and the restriction of the grain boundary sliding because the addition of cerium reduced the segregation of sulfur at grain boundaries and refined the grain structure. The occurrence and acceleration of dynamic recrystallization were found to be responsible for the high hot ductility of the alloy with 0.016% cerium at 1 000℃ and the alloy with 0. 024% cerium at 950 - 1 000℃ as a result of the refinement of the grain structure by addition of cerium.
文摘The effect of Ce, La and mischmetal on the solidification structure of Fe-36Ni invar alloy was investigated. The results show that great amounts of high-melting point compounds ( Ce2O3, La202S and ( Ce, La)2O2S ) respectively formed in the alloy with the addition of Ce, La or mischmetal. Based on the theory of lattice misfit, the lattice misfit between the (0001) surfaces of Ce2O3,Ce2O2S and La2O2S and (100) surface of Fe-36Ni invar alloy were 6.21%, 5.77 % and 5.42 %, respectively, which are relatively low. Therefore, Ce2 O3, La2 O2 S and ( Ce, La) 2 O2 S could serve as the core of heterogeneous nucleation, improve the equiaxed grain ratio, reduce the equiaxed grain size and refine the solidification structure of alloy.
基金the National Natural Science Foundation of China(Nos.51874211 and 51325102)。
文摘The Fe-Ni36 alloy was prepared via the one-step electrolysis of a mixed oxides precursor in a molten Na2CO3-K2CO3 eutectic melt at 750℃,where porous Fe_(2)O_(3)-NiO pellets served as the cathode and the Ni10 Cu11 Fe alloy was an inert anode.During the electrolysis,Ni O was preferentially electro-reduced to Ni,then Fe_(2)O_(3)was reduced and simultaneously alloyed with nickel to form the Fe-Ni36 alloy.Different cell voltages were applied to optimize the electrolytic conditions,and a relatively low energy consumption of 2.48 k W·h·kg^(-1) for production of Fe Ni36 alloy was achieved under 1.9 V with a high current efficiency of 94.6%.The particle size of the alloy was found to be much smaller than that of the individual metal.This process provides a low-carbon technology for preparing the Fe-Ni36 alloy via molten carbonates electrolysis.
文摘Effects of Ti-Ce refiners on the solidification structure and the hot ductility of Fe-36Ni invar alloy were investigated, the corresponding mechanisms were also discussed. The results showed that the solidification of the alloy was remarkably refined with the addition of 0.05%Ti-0.01%Ce refiners. Not only did the columnar grains become shorter and thinner, but the growth pattern of them changed into staggered growth from linear growth. The alloy had a bad hot ductility below 1050 °C, which was mainly attrib-uted to weaker boundaries and the presence of grain boundary sliding. However, the hot ductility of the alloy was highly enhanced at 850-1000 °C as the addition of 0.05%Ti-0.01%Ce refiners could refine grain sizes, thus hinder grain boundary sliding, strengthen the grain boundary and promote the grain boundary movement. The alloy had a good hot ductility over 1050 °C, dynamic recrys-tallization occurred and was found to be responsible for the better hot ductility. In addition, the average coefficient of thermal ex-pansion of the alloy decreased a little with the addition of 0.05%Ti-0.01%Ce refiners, which met the requirement of material prop-erties.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIP)(No.2015R1A2A1A15054116)
文摘Invar alloy consisting of 64% iron and 36% nickel has been widely used for the production of shadow masks for organic light emitting diodes(OLEDs) because of its low thermal expansion coefficient(1.86 × 10^-6cm/°C).To fabricate micro-hole arrays on 30 lm invar alloy film,through-mask electrochemical micromachining(TMEMM) was developed and combined with a portion of the photolithography etching process.For precise hole shapes,patterned photoresist(PR) film was applied as an insulating mask.To investigate the relationship between the current density and the material removal rate,the principle of the electrochemical machining was studied with a focus on the equation.The finite element method(FEM) was used to verify the influence of each parameter on the current density on the invar alloy film surface.The parameters considered were the thickness of the PR mask,inter-electrode gap(IEG),and electrolyte concentration.Design of experiments(DOE) was used to figure out the contribution of each parameter.A simulation was conducted with varying parameters to figure out their relationships with the current density.Optimization was conducted to select the suitable conditions.An experiment was carried out to verify the simulation results.It was possible to fabricate micro-hole arrays on invar alloy film using TMEMM,which is a promising method that can be applied to fabrications of OLEDs shadow masks.
文摘Measurements of magnetic susceptibility in mechanically alloyed Fe-Ni Invar alloys were taken under pressures up to 7.5GPa. The rate of decrease in the Curie temperature for 700℃ annealed specimen was larger than that annealed at 1000℃. This result can be explained by considering the fact that the width of the concentration fluctuation becomes larger in the specimen annealed at lower temperature.
基金supported financially by the National Key Research and Development Program of China(No.2019YFA0705300)the Guangdong Special Support Program(No.2019BT02C629)+6 种基金the National Natural Science Foundation of China(No.51690160)the Shanghai Science and Technology Committee(No.19DZ1100704)the Shanghai Sailing Program(No.19YF1415900)Golden Apple Project of Baosteel Co.,Ltd(No.A19EC13500)the Guangdong Basic and Applied Basic Research Foundation(No.2019B1515120016)the Guangzhou Science and Technology Program(Nos.202002030290 and 202007020008)the GDAS’Project of Science and Technology Development(Nos.2019GDASYL-0503006 and 2020GDASYL-20200302011)。
文摘In this work,the Invar 36 alloys were manufactured using cold spray(CS)additive manufacturing technique.The systematic investigations were made on the microstructural evolution,thermal expansion and mechanical properties under as-sprayed(AS)and heat-treated(HT)conditions.XRD(X-ray diffraction)and ICP-AES(inductively coupled plasma atomic emission spectroscopy)analyses show that no phase transformation,oxidation,nor element content change have occurred.The X-ray computed tomography(XCT)exhibited a near fully dense structure with a porosity of 0.025%in the helium-produced sample under as-sprayed condition,whereas the nitrogen-produced samples produced at 5 MPa and 800℃show more irregular pore defects.He-AS sample shows a more prominent grain refinement than that of nitrogen samples due to the more extensive plastic deformation.The post heat-treatment exhibited a promoted grain growth,inter-particle diffusion,as well as the formation of annealing twins.Between25℃and 200℃,the nitrogen samples possessed lower CTE(coefficient of thermal expansion)values(1.53×10^(-6)/℃)compared with those produced by casting and laser additive manufacturing.The He-AS samples exhibited a noticeable negative CTE value between 25℃and 200℃,which may due to the significant compressive residual stress(-272 MPa)compensating its displacement with temperature increase during CTE test.The N2-HT and He-HT Invar 36 samples present a notable balance between strength and ductility.In conclusion,the CS technique can be considered as a potential method to produce the Invar36 component with high thermal and mechanical performance.
基金supported by the National Nature Science Foundation of China (Grant Nos. 51372049, 51321061 and U1537206)
文摘Porous Si3N4 was brazed to Invar alloy in this study, and Ag-Cu-Ti/Cu/Ag-Cu multi-layered filler was designed to inhibit the formation of Fe2Ti and Ni3Ti intermetallic compounds. The effects of the brazing temperature and the thickness of Cu interlayer on the microstructure and mechanical properties of brazed joints were investigated. The typical microstructure of the joint brazed with multi-layered filler was porous Si3N4/TiN + Ti5Si3/Ag-Cu eutectic[Cu[Ag-Cu eutectic/Cu-rich layer + diffusion layer/Invar. When the brazing temperature increased, the reaction layer at the ceramic/filler interface grew thicker and the Cu interlayer turned thinner. As the thickness of Cu interlayer increased from 50 to 150 μm, the joint strength first increased and then decreased. In this research, the maximum shear strength (73 MPa) was obtained when being brazed at 1173 K with a 100 μm Cu interlayer applied in the filler, which was 55% higher than that brazed with single Ag-Cu-Ti brazing alloy and had reached 86% of the ceramic. The release of residual stress and the barrier effect of Cu interlayer to inhibit the formation of Fe2Ti and Ni3Ti intermetallics played the major role in the improvement of joint strength.