AlCoCrFeNiTi0.5高熵合金的组织控制和腐蚀性能

Microstructure Control and Corrosion Properties of AlCoCrFeNiTi0.5 High-Entropy Alloy

摘要:

研究冷坩埚悬浮熔炼AlCoCrFeNiTi0.5多组元高熵合金的微观组织及回火工艺对合金组织、硬度和电化学性能的影响规律。结果发现，冷坩埚悬浮熔炼AlCoCrFeNiTi0.5高熵合金铸锭中晶粒呈树枝晶长大并析出少量ω相。随回火温度的升高，晶粒长大，共晶组织增多，BCC相强度呈先下降后升高趋势。800 ℃时，合金树枝晶晶粒变得细小，之后随着温度的升高，枝晶间的元素偏析减弱。合金具有较强的抗回火软化能力。在3.5%NaCl溶液中，孔蚀主要集中在树枝晶与共晶组织α相的交接处，回火后合金的耐蚀性均优于铸态合金，700 ℃回火后合金的耐腐蚀性能比铸态及其它合金更强。

Abstract:

The microstructures, hardness and electrochemical properties of AlCoCrFeNiTi0.5 high-entropy alloys fabricated by cold crucible levitation melting (CCLM) with as-cast structure and tempering treated structures were investigated. The results show that in contrast to suction casting using copper molds, CCLM causes the growth of dendrite phase and separation of ω phase. As the increase of temperature, the dendrite grains grow up, the amount of eutectic structures increases, and the intensity of BCC peak shows a rising trend after the first drop. At the temperature of 800 ℃, the dendrite grains become refined. And then, as the temperature increases, the element segregation of interdendrite is weakened. The alloy exhibits a superior resistance to tempering and softening property. Furthermore, pitting corrosions are mainly concentrated in the place between dendrite phase and eutectic α phase. The tempering treatment improves corrosion properties in a 3.5% NaCl solution, and the alloy tempered at 700 exhibits the best corrosion property among the experimental alloys.