高熵合金FeCrCoNiMn热浸铝熔体的界面结构及组织形成机制研究

Interface Structure and Formation Mechanism of FeCrCoNiMn High Entroy Alloy Hot-dipping in Molten Aluminum

用真空电弧炉制备了铸态高熵合金FeCrCoNiMn（HEA）,将高熵合金在700℃铝熔体中进行了不同时间（0～1h）的保温热浸实验,分析了HEA-Al固/液界面反应的组织演变及形成机理。结果表明,高熵合金在铝熔体中热浸反应时,其界面附近可形成由Al_（86）Cr_（13.5）Fe_（6.5）、Al_（86）Mn_（14）、Al_3Ni和Al_9Co_2多种富铝金属间化合物组成的反应层、富铝块体相以及含Fe和Ni的富铝层状析出相和网状结构组织。热浸初期,界面反应层的形成和长大主要受高熵合金表面元素的溶解和脱嵌过程控制,此时反应层和块体相的形成和长大主要位于铝溶体一侧且反应层界面迁移速率较快;形成反应层后,反应层厚度随热浸反应时间的延长而增大,当反应时间t〉10min后,反应层厚度基本维持在20μm左右不再变化,此时反应层界面迁移速率有所变缓。

The as-cast FeCrCoNiMn high-entroy alloy was prepared by arc furnace in vacuum and the alloy was immersed in the molten aluminum at 700 ℃with different times（0-1h）.Microstructure evolution and phase formation mechanism in HEA/Al interface were investigated.The results showed that when the high-entroy alloy was immersed in the molten Al,a region with complicated microstructure including the reaction layer with Al-rich intermetallic Al_（86）Cr_（13.5）Fe_（6.5）,Al_（86）Mn_（14）,Al_3Ni and Al_9Co_2 phase at the HEA/Al interface,bulk phase containing high concentration of Cr and Mn,lamellar precipitate and net structure in solidified Al could be formed.At the beginning of the hot dipping,the formation and growth of the reaction layer was controlled by dissolving and exfoliation of high-entroy alloy elements,meanwhile the layer was mainly located in Al side and migrated rapidly.After the reaction layer is formed,the layer thickness increased with the increase of the dipping time.When dipping time is more than 10 min,the thickness of the reaction layer was basically maintained at about 20μm and the migration rate of the reaction layer became slowly.