In this study,the tensile creep behavior of a hot-rolled Mg-4Y-3.5Nd alloy subjected to different prior thermo-mechanical treatments was investigated at 220℃.Five groups of samples were prepared using different combi...In this study,the tensile creep behavior of a hot-rolled Mg-4Y-3.5Nd alloy subjected to different prior thermo-mechanical treatments was investigated at 220℃.Five groups of samples were prepared using different combinations of the solid solution(S),aging treatment at 220℃ for 30 h(A),and hot compression at 490℃ to a true strain of 0.25(C).The abbreviations for the samples are S,SA,SC,SAC,and SCA.Upon examining the yield strength and creep resistance,it was found that creep resistance could not be directly predicted by the yield strength.The stability of the deformation bands(DBs)induced by prior thermo-mechanical treatment plays an important role in determining the creep resistance.The dislocation of the DBs and demonstrated the best creep resistance in the SAC sample,which were prepared using a solid solution,aging treatment,and subsequent hot compression.However,despite the highest yield strength,frequent dislocation motions destroyed the stability of the DBs and deteriorated the creep resistance of the SCA sample,which were prepared using a solid solution,hot compression,and subsequent aging treatment.Among the thermo-mechanical treatments used in this study,the application of aging treatment was important to obtain the resultant creep resistance.When the aging treatment was performed prior to hot compression,the creep resistance could be further enhanced based only on hot compression.Accordingly,the sequence from the strongest to the weakest creep resistance was SAC>SC>S>SCA>SA.展开更多
This work concerns the distinguished roles of static aging and strain aging in the creep resistance of a hot-rolled Mg-4Y-3.5Nd alloy.The solution-treated sample is named AS while the peak-aged sample ob-tained from s...This work concerns the distinguished roles of static aging and strain aging in the creep resistance of a hot-rolled Mg-4Y-3.5Nd alloy.The solution-treated sample is named AS while the peak-aged sample ob-tained from static aging at 220℃ is named AA.The strain aging(creep loading)was performed for both AS and AA samples at 220,250 and 280℃,respectively.The results showed that the creep resistance of both samples was closely related to the width of precipitate-free zones(PFZs).Under low stress,the dislocation cross-slip was effectively delayed by the precipitates and the existing PFZs widened slowly in the AA sample,leading to its stronger creep resistance compared to the AS sample.Inversely,under high stress,pyramidal<c+a>slip was more frequently activated,which could not be delayed by the coars-ened precipitates.Consequently,the widening rate of PFZs became fast and the creep resistance became weaker in the AA sample.From the above-mentioned results,this work provides a novel guide for using Mg alloys with rare-earth addition.At the temperature range of 220-280℃,static aging is positive for creep resistance under low stress,while directly performing strain aging without static aging is recom-mended for creep resistance under high stress.展开更多
基金support received from the National Key Research and Development Program of China(Grant No.2022YFE0109600)the National Natural Science Foundation of China(Grant Nos.51974376 and 52071344)+1 种基金the Natural Science Foundation of Hunan Province(Grant No.2021JJ20063)the Distinguished Professor Project of Central South University(Grant No.202045009).
文摘In this study,the tensile creep behavior of a hot-rolled Mg-4Y-3.5Nd alloy subjected to different prior thermo-mechanical treatments was investigated at 220℃.Five groups of samples were prepared using different combinations of the solid solution(S),aging treatment at 220℃ for 30 h(A),and hot compression at 490℃ to a true strain of 0.25(C).The abbreviations for the samples are S,SA,SC,SAC,and SCA.Upon examining the yield strength and creep resistance,it was found that creep resistance could not be directly predicted by the yield strength.The stability of the deformation bands(DBs)induced by prior thermo-mechanical treatment plays an important role in determining the creep resistance.The dislocation of the DBs and demonstrated the best creep resistance in the SAC sample,which were prepared using a solid solution,aging treatment,and subsequent hot compression.However,despite the highest yield strength,frequent dislocation motions destroyed the stability of the DBs and deteriorated the creep resistance of the SCA sample,which were prepared using a solid solution,hot compression,and subsequent aging treatment.Among the thermo-mechanical treatments used in this study,the application of aging treatment was important to obtain the resultant creep resistance.When the aging treatment was performed prior to hot compression,the creep resistance could be further enhanced based only on hot compression.Accordingly,the sequence from the strongest to the weakest creep resistance was SAC>SC>S>SCA>SA.
基金supported by the National Key Research and Development Program of China(Nos.2022YFE0109600 and 2021YFB3701100)the National Natural Science Foundation of China(Nos.51974376 and 52071344)the Natural Science Foundation of Hunan Province(No.2021JJ20063).
文摘This work concerns the distinguished roles of static aging and strain aging in the creep resistance of a hot-rolled Mg-4Y-3.5Nd alloy.The solution-treated sample is named AS while the peak-aged sample ob-tained from static aging at 220℃ is named AA.The strain aging(creep loading)was performed for both AS and AA samples at 220,250 and 280℃,respectively.The results showed that the creep resistance of both samples was closely related to the width of precipitate-free zones(PFZs).Under low stress,the dislocation cross-slip was effectively delayed by the precipitates and the existing PFZs widened slowly in the AA sample,leading to its stronger creep resistance compared to the AS sample.Inversely,under high stress,pyramidal<c+a>slip was more frequently activated,which could not be delayed by the coars-ened precipitates.Consequently,the widening rate of PFZs became fast and the creep resistance became weaker in the AA sample.From the above-mentioned results,this work provides a novel guide for using Mg alloys with rare-earth addition.At the temperature range of 220-280℃,static aging is positive for creep resistance under low stress,while directly performing strain aging without static aging is recom-mended for creep resistance under high stress.
