Abstract A single-phase body-centered cubic (BCC) HfNbTiZr refractory high-entropy alloy (RHEA) was fabricated by vacuum arc melting. The effect of aging at 450 °C on 80% cold-rolled HfNbTiZr specimens (abbr. as CRA) as well as that on 80% cold-rolled and then recrystallized at 1000 °C for 1 h (abbr. as CRRA) have been investigated. A significant increase of hardness after aging at 450 °C was presented in both CRA and CRRA specimens. The hardness of CRA specimens increased dramatically within a shorter time than that of CRRA specimens, indicating that the cold-rolled process can significantly enhance the age hardening effect. During aging at 450 °C, BCC and hexagonal closed-packed (HCP) precipitates formed in the BCC matrix. The particle-like Nb-rich BCC precipitates were mainly within the grains and needle-like HfTiZr HCP precipitates mostly located near the grain boundaries. In CRA specimens aged for 500 h, BCC precipitates could grow up to 30–90 nm in radius and HCP precipitates to 300–1600 nm in length and 40–140 nm in width. The results of tensile test revealed that the presence of the precipitates can induce brittleness in HfNbTiZr alloy.

中文翻译：

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严重冷轧和中温时效HfNbTiZr难熔高熵合金的研究

摘要 采用真空电弧熔炼方法制备了单相体心立方（BCC）HfNbTiZr难熔高熵合金（RHEA）。450 °C 时效对 80% 冷轧 HfNbTiZr 试样（缩写为 CRA）的影响以及对 80% 冷轧然后在 1000 °C 下再结晶 1 h（缩写为 CRRA）的影响调查。CRA 和 CRRA 试样在 450 °C 时效后硬度显着增加。CRA 试样的硬度在比 CRRA 试样更短的时间内显着增加，表明冷轧工艺可以显着增强时效硬化效果。在 450 °C 时效期间，BCC 和六方密堆积 (HCP) 沉淀物在 BCC 基体中形成。颗粒状富含 Nb 的 BCC 析出物主要位于晶粒内，针状 HfTiZr HCP 析出物主要位于晶界附近。在老化 500 小时的 CRA 试样中，BCC 沉淀物的半径可达 30-90 nm，HCP 沉淀物的长度可达 300-1600 nm，宽度可达 40-140 nm。拉伸试验结果表明，析出物的存在会导致 HfNbTiZr 合金脆化。