放电等离子烧结MoNbTaW难熔高熵合金

Preparation of MoNbTaW Refractory High-Entropy Alloys by Spark Plasma Sintering

摘要:

以纯金属元素粉末为原料,采用放电等离子烧结工艺制备了MoNbTaW难熔高熵合金,研究了烧结温度和保温时间等工艺参数对MoNbTaW难熔高熵合金的物相、晶体结构、烧结行为和力学性能的影响。结果表明,在烧结温度1800℃和保温5min即可形成BCC单相高熵合金；烧结温度是影响MoNbTaW难熔高熵合金致密度、晶粒尺寸和力学性能的主要因素；随着烧结温度的升高,合金的晶粒尺寸增大,致密度、硬度和和屈服强度均增高；烧结温度为2000℃时合金的致密度可达99.8%,化学成分无偏析,屈服强度为1314±14MPa,断裂韧性为(5～6)MPa.m_1/2,其断裂模式为解理断裂。

Abstract:

The MoNbTaW refractory high-entropy alloys were prepared by spark plasma sintering using pure metal powders as raw materials. The effects of technological parameters on the phase, crystal structure, sintering behavior and mechanical properties of MoNbTaW refractory high-entropy alloys were studied. The results show that the single-phase BCC high-entropy alloy can be formed at the sintering temperature of 1800 °C with the holding time of 5 min. The sintering temperature is the most important factor that affects the density, grain size and mechanical properties of the MoNbTaW refractory high-entropy alloy. When the sintering temperature is 2000 °C, the density of the alloy is 99.8 %, and the yield strength is 1314±14 MPa, the fracture toughness is (5～6)MPa.m_1/2. The MoNbTaW refractory high-entropy alloy prepared by spark plasma sintering process have no chemical composition segregation and is a brittle material with the fracture mode of cleavage fracture.