热压烧结(FeNiCoCr)_(100-x)Al_(x)(x=0、5)高熵合金的微观组织及力学性能

Microstructure and Mechanical Properties of High-entropy Alloys(FeNiCoCr)_(100-x)Al_(x)(x=0,5)Prepared by Hot-pressing Sintering

采用低能球磨-热压烧结制备了(FeNiCoCr)_(100-x)Al_(x)(x=0、5)高熵合金,并对其进行时效处理,研究了合金的组织结构与力学性能。结果表明:烧结态及时效态合金的微观组织均由FCC相和少量BCC相构成,其中FCC相中均存在孪晶,且未添加Al的合金中孪晶比例相对较高;添加Al的合金中BCC相较高,且时效处理后出现了大量小角度晶界。时效态FeNiCoCr合金具有最佳的综合性能,其压缩真屈服强度达545 MPa,弯曲强度和断裂韧性分别为1342±20 MPa和32.5±2.0 MPa·m^(1/2),优异的力学性能归因于FCC相中退火孪晶的形成以及BCC相的析出。

The high-entropy alloys(FeNiCoCr)_(100-x)Al_(x)(x=0,5)were prepared via a two-step process i.e.,low-energy ball milling and then vacuum hot-pressing sintering,while the alloys were post-aged,afterwards,their microstructure and mechanical properties were assessed.The results show that the microstructure of both the as-sintered and the aged alloys composed of fcc-phase and a small amount of bcc phase,but twins presented in the fcc phase,and the proportion of twins for the alloy without Al was relatively high.The alloy with Al had relatively high bcc phase,and many small-angle grain boundaries appeared after aging treatment.The aged FeNiCoCr alloy has the best comprehensive performance,with a compressive true yield strength of 545 MPa.Moreover,the bending strength and the fracture toughness of the aged FeNiCoCr alloy reached 1342 MPa and 32.5 MPa·m^(1/2).The excellent mechanical properties were attributed to the generation of annealing twins in the fcc-phase and the precipitation of the bcc-phase.