摘要
采用定向凝固在3μm/s、5μm/s、10μm/s和50μm/s抽拉速率下制备了Ni43.9Co22.4Fe8.8Al10.7Ti11.7B2.5高熵合金,对其组织演变及力学性能进行了研究,揭示了该高熵合金定向凝固固液界面转变机制与强化机理。结果表明:Ni43.9Co22.4Fe8.8Al10.7Ti11.7B2.5高熵合金为单一FCC固溶体相,随抽拉速率增大,固液界面发生由胞状枝晶、胞状树枝晶到树状枝晶的转变,一次间距及晶粒尺寸均减小。抗压强度和压缩应变均随抽拉速率增加而增大,在50μm/s下最大压缩应变达到35.11%,最大抗压强度达到2369.41 MPa。抽拉速率提高和迟滞扩散效应导致固液界面胞枝转变;树状枝晶中明显增多的晶界阻碍位错滑移,导致变形中位错在晶界处塞积,晶界强化在定向凝固Ni43.9Co22.4Fe8.8Al10.7Ti11.7B2.5高熵合金中起到重要作用。此外,由于Ni、Co、Fe与其他原子半径差产生晶格畸变及固溶强化效应。
Ni43.9Co22.4Fe8.8Al10.7Ti11.7B2.5 high entropy alloy was prepared by directional solidification at different withdrawal rates(3μm/s,5μm/s,10μm/s and 50μm/s),and the microstructure evolution and mechanical properties were investigated,revealing the transformation mechanism of solid-liquid interface and strengthening mechanism for directional solidification of this high entropy alloy.The results show that Ni43.9Co22.4Fe8.8Al10.7Ti11.7B2.5 high entropy alloy is a single FCC solid solution phase.With the increase of withdrawal rate,the morphology of solid-liquid interface transforms from cellular through cellular-dendritic to dendritic,and both the primary spacing and grain size decrease.The compressive strength and strain both increase with increasing withdrawal rate.The compressive strength and strain reach a maximum strain of 35.11%and a maximum compressive strength of 2369.41 MPa at 50μm/s.It is found that the sluggish diffusion effect and the increasing of withdrawal rate give rise to the cellular/dendrite morphology evolution of the solid-liquid interface.The significant increase of grain boundaries in the dendrite morphology hinders the dislocation slip,resulting in dislocation plugging and accumulation at the grain boundaries during deformation.The grain boundary strengthening plays an important role in enhancing of directionally solidified Ni43.9Co22.4Fe8.8Al10.7Ti11.7B2.5 high entropy alloy.In addition,the radius difference between Ni,Co,Fe and other atoms results in lattice distortion and the solid solution strengthening effect.
作者
徐义库
常锦睿
张经纬
严凯
邹嘉缘
田天啸
赵秦阳
陈永楠
XU Yi-ku;CHANG Jin-rui;ZHANG Jing-wei;YAN Kai;ZOU Jia-yuan;TIAN Tian-xiao;ZHAO Qin-yang;CHEN Yong-nan(School of Materials Science and Engineering,Chang’an University,Xi’an 710064,China)
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2023年第11期3754-3766,共13页
The Chinese Journal of Nonferrous Metals
基金
中央高校基本科研业务费专项资金资助项目(300102311401)
陕西省重点研发项目−揭榜挂帅项目(2022JBGS2-01)
长安大学创新创业训练计划资助项目(202110710317)。
关键词
高熵合金
定向凝固
固液界面
压缩性能
晶界强化
high entropy alloy
directional solidification
solid-liquid interface
compressive property
grain boundary strengthening
