摘要
Al-FeCoNiCrAl high entropy alloy(HEA) composite coatings were prepared on Ti-6Al-4V via highenergy mechanical alloying(MA). The microstructures and phase composition of the coatings were studied. A continuous and dense coating could be fabricated at a ratio of 35%(weight fraction)Al-FeCoNiCrAl after 4 h milling.The results showed that the thickness of the composite coatings increased first and then decreased with the increase of milling time. And the hardness of coating increased with the increase of milling time. The phase changed during the annealing process. Part of the initial body-centered cubic(BCC)phase of the composite coatings changed into the L12 phase,(Ni,Co)3Al4 and σ phase after annealing above 550 ℃. Ordered BCC was found in the coatings after annealing above 750 ℃. Only BCC and ordered BCC appeared in coatings after annealing above 1 050 ℃. The hardness of the coatings after annealing at 550 ℃ and 750 ℃ was higher than before because of spinodal decomposition and high hardness σ phase. The hardness of the coatings after annealing at 1 050 ℃ decreased because residual stress released.
采用机械合金化法在TC4钛合金基体上成功制备了均匀致密的Al-FeCoNiCrAl高熵合金复合涂层,研究了退火对复合涂层物相组成和性能的影响,建立起退火温度与复合涂层物相演变和性能之间的内在关系。结果表明:涂层厚度随着球磨时间增加先增加后减小,并且涂层硬度随着球磨时间增加而增加。涂层的物相随退火温度变化而变化,复合涂层为BCC相,550℃退火2 h后涂层中生成了L12相,σ相和(Ni,Co)3Al4。750℃退火后涂层中生成有序BCC相。1050℃退火后涂层中仅存BCC相和有序BCC相。在550℃和750℃退火后涂层的硬度略微升高,1050℃退火后涂层硬度降低。
