Guo Lin, Wu Wenqian, Ni Song, Wang Zhangwei, Song Min
State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China.
Thayer School of Engineering, Dartmouth College, NH 03755, USA.
Micron. 2017 Oct;101:69-77. doi: 10.1016/j.micron.2017.06.007. Epub 2017 Jun 21.
An AlCrCuFeNi high entropy alloy (HEA) was prepared by arc melting, followed by annealing at different temperatures. The elemental distributions, phase formation, morphology and microstructural evolution of the HEA in both the as-cast state and annealed state were investigated. The results indicate that the HEA undergoes elements segregation, precipitation and spinodal decomposition. The as-cast alloy consists of Cr-Fe-Ni rich FCC dendritic (DR) phase and BCC interdendritic (ID) phase. Spherical Fe-Cr rich BCC precipitates were found to disperse in Al-Ni rich B2 (ordered BCC) matrix. After heat treatments, the distribution of elements clearly changes, along with changes of the constituent phase and morphology. After annealing at 600°C, the DR region remains Cr-Fe-Ni rich phase, while some spherical precipitates transform into the needle-like structure within the ID region. The L1 (ordered FCC) nanorod-shaped phase ((Ni,Cu)Al) and plate-like Al-Ni rich phase form within the DR region when annealing up to 900°C. The L1 phase almost dissolves in the FCC matrix due to the order-disorder transition and an obvious coarsening of the Fe-Cr rich phase occurs after annealing at 1100°C. The segregation of Cu atoms at the interface between DR and ID regions is found at the as-cast state, while a uniform distribution of Cu atoms in DR and ID regions was observed after annealing at 1100°C.
通过电弧熔炼制备了一种AlCrCuFeNi高熵合金（HEA），随后在不同温度下进行退火处理。研究了该高熵合金在铸态和退火态下的元素分布、相形成、形态和微观结构演变。结果表明，该高熵合金经历了元素偏析、析出和旋节分解。铸态合金由富Cr-Fe-Ni的面心立方树枝状（DR）相和体心立方枝晶间（ID）相组成。发现球形富Fe-Cr的体心立方析出物分散在富Al-Ni的B2（有序体心立方）基体中。热处理后，元素分布明显变化，同时组成相和形态也发生变化。在600°C退火后，DR区域仍为富Cr-Fe-Ni相，而ID区域内一些球形析出物转变为针状结构。当退火温度达到900°C时，DR区域内形成L1（有序面心立方）纳米棒状相（(Ni,Cu)Al）和板状富Al-Ni相。由于有序-无序转变，L1相几乎溶解在面心立方基体中，并且在1100°C退火后，富Fe-Cr相明显粗化。在铸态时发现Cu原子在DR和ID区域之间的界面处偏析，而在1100°C退火后观察到Cu原子在DR和ID区域中均匀分布。
