摘要
目的制备大尺寸(CrCoNi)_(94)Al_(3)Ti_(3)中熵合金(MEAs),并研究其凝固行为。方法利用水冷铜坩埚悬浮熔炼技术制备大尺寸铸锭,通过金相(OM)、扫描电子显微镜(SEM)、能谱(EDS)等手段表征合金不同半径处的凝固组织和偏析行为,并采用Jmpro数值模拟软件预测合金可能存在的相,揭示大尺寸(CrCoNi)_(94)Al_(3)Ti_(3)MEA的凝固特点。结果大尺寸(CrCoNi)_(94)Al_(3)Ti_(3)MEA的凝固组织为典型柱状树枝晶,随着冷却速率的变化,柱状晶形态和尺寸发生了明显变化。在凝固过程中,Ni、Al、Ti元素表现为枝晶间偏析,随着冷却速率的降低,偏析程度逐渐增大。(CrCoNi)_(94)Al_(3)Ti_(3)基体为面心立方结构(FCC),在枝晶间(ID)存在少量块状的η相金属间化合物(Ni,Co)3(Al,Ti),同时在ID区域形成了大量不同纳米尺寸的L1_(2)相。结合相图可知,大尺寸(CrCoNi)_(94)Al_(3)Ti_(3) MEA的凝固路径为L→L+γ→L+γ+η→γ+η→γ+γ'+η。结论水冷铜坩埚悬浮熔炼技术制备的大尺寸(CrCoNi)_(94)Al_(3)Ti_(3)MEA无宏观偏析,该技术可以作为工程应用手段。
The work aims to prepare large-sized(CrCoNi)_(94)Al_(3)Ti_(3) medium entropy alloy(MEAs)and study its solidification behavior.Large-sized ingots were prepared by water-cooled copper crucible levitation melting.Solidification structure and seg-regation behavior of alloys at different radii were analyzed with an optical microscope(OM),a scanning electron microscopy(SEM)and an energy dispersive spectroscopy(EDS).The possible phase of alloy was predicted with Jmpro numerical simula-tion software to reveal the solidification characteristics of large-sized(CrCoNi)_(94)Al_(3)Ti_(3) MEA.The solidification structure of the large-sized(CrCoNi)_(94)Al_(3)Ti_(3) MEA was typical columnar dendritic structure.The morphology and size of columnar crystals changed significantly with cooling rate.During the solidification,Ni,Al,and Ti elements exhibited interdendritic segregation,and the degree of segregation gradually increased with the decrease of cooling rate.The(CrCoNi)_(94)Al_(3)Ti_(3) MEA matrix was a face centered cubic structure(FCC).There were a small number of blockyηphase intermetallic compounds(Ni,Co)3(Al,Ti)in the dendrites(ID).Moreover,a large number of L1_(2) nano-phases was observed in the ID area.The solidification path of(CrCoNi)_(94)Al_(3)Ti_(3) MEA was L→L+γ→L+γ+η→γ+η→γ+γ'+ηaccording to phase diagram calculation and microstructure evolution.The large-sized(CrCoNi)_(94)Al_(3)Ti_(3) MEA prepared with the water-cooled copper crucible suspension melting technology has no macroscopic segregation,which could be used for engineering application.
作者
陆杰波
吴博
马腾飞
王晓红
李傲
董多
朱冬冬
LU Jie-bo;WU Bo;MA Teng-fei;WANG Xiao-hong;LI Ao;DONG Duo;ZHU Dong-dong(Key Laboratory of Air-driven Equipment Technology of Zhejiang Province,Quzhou University,Zhejiang Quzhou 324000,China)
出处
《精密成形工程》
北大核心
2023年第10期60-66,共7页
Journal of Netshape Forming Engineering
基金
国家自然科学基金(52001262,52071188,52171120)。
关键词
中熵合金
悬浮熔炼
凝固行为
组织演变
medium entropy alloy
levitation melting
solidification behavior
microstructure evolution
