The Mg-7Gd-4Y-2Zn-0.5Zr alloy chips were successfully recycled through isothermal sintering and equal channel angular pressing(ECAP).The mechanical properties and microstructure evolution of samples during the recycli...The Mg-7Gd-4Y-2Zn-0.5Zr alloy chips were successfully recycled through isothermal sintering and equal channel angular pressing(ECAP).The mechanical properties and microstructure evolution of samples during the recycling process were studied in detail.The eutectic phases in the as-cast alloy transform into long period-stacking ordered(LPSO)phases after homogenization,which can improve the plasticity of the material.After isothermal sintering,the density of the sample is lower than that of the homogenized sample,and oxide films are formed adjacent to the bonding interface of the metal chips.Hence,the plasticity of the sintered sample is poor.Dense samples are fabricated after ECAP.Although the grains are not refined compared to the sintered sample,the microstructure becomes more uniform due to recrystallization.Fiber interdendritic LPSO phase and kinked 14H-LPSO phase are formed in the alloy due to the shear deformation during the ECAP process,which improves the strength and plasticity of the sample significantly.Furthermore,the basal texture is weakened due to the Bc route of the ECAP process,which can increase the Schmid factor of the basal slip system and improve the elongation of the sample.After 2 ECAP passes,the fully densified recycled billet shows superior mechanical properties with an ultimate tensile strength of 307.1 MPa and elongation of 11.1%.展开更多
Machined chips of Mg-Zn-Y-Zr alloy were consolidated by cold pressing and then hot extrusion under various processing temperatures and extrusion ratios. The results show that the microstructure of the chip-extruded al...Machined chips of Mg-Zn-Y-Zr alloy were consolidated by cold pressing and then hot extrusion under various processing temperatures and extrusion ratios. The results show that the microstructure of the chip-extruded alloy is marked by a large number of recrystallized grains and some unrecrystallized grains, which results in high strength but low ductility at temperatures below 320 ℃. With increasing processing temperature up to 360 ℃, entirely recrystallized and equiaxed grains are obtained. Mg-Zn-Y-Zr alloy with low strength but high ductility is obtained compared with the alloy processed at low temperature. At 420℃, coarse and equiaxed grains are formed, which results in the drastic decrease of mechanical properties. With increasing extrusion ratio from 8 to 16, the grain refinement is more obvious and the mechanical properties at room temperature are improved effectively. However, the yield strength and ultimate tensile strength are improved a little with further increasing extrusion ratio.展开更多
The consolidation Mg-Gd-Y-Zn-Zr billets containing long period-stacking ordered(LPSO)phase were recycled from the metal chips through the spark plasma sintering(SPS)process,which achieves the effective metallurgical b...The consolidation Mg-Gd-Y-Zn-Zr billets containing long period-stacking ordered(LPSO)phase were recycled from the metal chips through the spark plasma sintering(SPS)process,which achieves the effective metallurgical bonding between metal chips.The effects of the sintering parameters on the microstructure characteristic and mechanical properties of the recycled billets were studied.The metal chips were effectively bonded in the recycled billets sintered at 500°C,however,the metal chips partly melted into semi-solid state as sintering temperature increased to 550°C.The oxidation films of rare earth(RE)element formed at the bond interface between metal chips during SPS recycling process.The consolidation recycled billets through SPS demonstrated the rival compression failure strain and superior compression stress compared with the referenced cast alloy.The lamellar 14H-LPSO phases hardly precipitate in the vicinity of the bond interface between metal chips after heat treatment with air cooling.However,the furnace cooling facilitates the precipitation of 14H-LPSO phases within the a-Mg grains,even the a-Mg matrix adjacent to the bond interface.The oxide films at the bond interface between the metal chips were zigzagged and fragmented during the isothermal compression.The cracks or holes were hardly observed adjacent to the bond interface during isothermal compression,which reveals superior bond properties and deformation consistency performance between metal chips.c 2020 Published by Elsevier B.V.on behalf of Chongqing University.展开更多
With the global warming of concern,the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits.In this work,re...With the global warming of concern,the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits.In this work,recycling of automotive aluminum is reviewed to highlight environmental benefits of aluminum recycling,use of aluminum alloys in automotive applications,automotive recycling process,and new technologies in aluminum scrap process.Literature survey shows that newly developed techniques such as laser induced breakdown spectroscopy(LIBS) and solid state recycling provide promising alternatives in aluminum scrap process.Compared with conventional remelting and subsequent refinement,solid state recycling utilizing compression and extrusion at room or moderate temperature can result in significant energy savings and higher metal yield.展开更多
基金supported by the fund of the National Natural Science Foundation of China(51875127,52275322).
文摘The Mg-7Gd-4Y-2Zn-0.5Zr alloy chips were successfully recycled through isothermal sintering and equal channel angular pressing(ECAP).The mechanical properties and microstructure evolution of samples during the recycling process were studied in detail.The eutectic phases in the as-cast alloy transform into long period-stacking ordered(LPSO)phases after homogenization,which can improve the plasticity of the material.After isothermal sintering,the density of the sample is lower than that of the homogenized sample,and oxide films are formed adjacent to the bonding interface of the metal chips.Hence,the plasticity of the sintered sample is poor.Dense samples are fabricated after ECAP.Although the grains are not refined compared to the sintered sample,the microstructure becomes more uniform due to recrystallization.Fiber interdendritic LPSO phase and kinked 14H-LPSO phase are formed in the alloy due to the shear deformation during the ECAP process,which improves the strength and plasticity of the sample significantly.Furthermore,the basal texture is weakened due to the Bc route of the ECAP process,which can increase the Schmid factor of the basal slip system and improve the elongation of the sample.After 2 ECAP passes,the fully densified recycled billet shows superior mechanical properties with an ultimate tensile strength of 307.1 MPa and elongation of 11.1%.
基金Project (51005217) supported by the National Natural Science Foundation of ChinaProject (20100480677) supported by China Postdoctoral Science Foundation
文摘Machined chips of Mg-Zn-Y-Zr alloy were consolidated by cold pressing and then hot extrusion under various processing temperatures and extrusion ratios. The results show that the microstructure of the chip-extruded alloy is marked by a large number of recrystallized grains and some unrecrystallized grains, which results in high strength but low ductility at temperatures below 320 ℃. With increasing processing temperature up to 360 ℃, entirely recrystallized and equiaxed grains are obtained. Mg-Zn-Y-Zr alloy with low strength but high ductility is obtained compared with the alloy processed at low temperature. At 420℃, coarse and equiaxed grains are formed, which results in the drastic decrease of mechanical properties. With increasing extrusion ratio from 8 to 16, the grain refinement is more obvious and the mechanical properties at room temperature are improved effectively. However, the yield strength and ultimate tensile strength are improved a little with further increasing extrusion ratio.
基金National Natural Science Foundation of China(Grant No.51875127).
文摘The consolidation Mg-Gd-Y-Zn-Zr billets containing long period-stacking ordered(LPSO)phase were recycled from the metal chips through the spark plasma sintering(SPS)process,which achieves the effective metallurgical bonding between metal chips.The effects of the sintering parameters on the microstructure characteristic and mechanical properties of the recycled billets were studied.The metal chips were effectively bonded in the recycled billets sintered at 500°C,however,the metal chips partly melted into semi-solid state as sintering temperature increased to 550°C.The oxidation films of rare earth(RE)element formed at the bond interface between metal chips during SPS recycling process.The consolidation recycled billets through SPS demonstrated the rival compression failure strain and superior compression stress compared with the referenced cast alloy.The lamellar 14H-LPSO phases hardly precipitate in the vicinity of the bond interface between metal chips after heat treatment with air cooling.However,the furnace cooling facilitates the precipitation of 14H-LPSO phases within the a-Mg grains,even the a-Mg matrix adjacent to the bond interface.The oxide films at the bond interface between the metal chips were zigzagged and fragmented during the isothermal compression.The cracks or holes were hardly observed adjacent to the bond interface during isothermal compression,which reveals superior bond properties and deformation consistency performance between metal chips.c 2020 Published by Elsevier B.V.on behalf of Chongqing University.
基金Project(FRINAT) supported by the Research Council of Norway (RCN)
文摘With the global warming of concern,the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits.In this work,recycling of automotive aluminum is reviewed to highlight environmental benefits of aluminum recycling,use of aluminum alloys in automotive applications,automotive recycling process,and new technologies in aluminum scrap process.Literature survey shows that newly developed techniques such as laser induced breakdown spectroscopy(LIBS) and solid state recycling provide promising alternatives in aluminum scrap process.Compared with conventional remelting and subsequent refinement,solid state recycling utilizing compression and extrusion at room or moderate temperature can result in significant energy savings and higher metal yield.