铸造与热压态CoCrW合金组织及力学性能的研究

Microstructure and Mechanical Properties of As-cast and Hot-pressed CoCrW Alloys

利用SEM、TEM、XRD、室温单向拉伸以及往复式球盘摩擦磨损等手段,对比研究了铸造与真空热压成型态CoCrW合金的组织及力学性能。结果表明,铸态CoCrW合金由三种相组成,分别为γ-Co、M12C和M23C6.热压态CoCrW合金由四种相组成,分别为γ-Co、Cr Co、M12C和M23C6.热压态CoCrW合金中存在原始颗粒边界及由硬质粒子"搭桥"而形成的孔隙,降低了热压态CoCrW合金的力学性能。铸态CoCrW合金的抗拉强度和断后伸长率均优于热压态CoCrW合金,硬度及耐磨性能则比热压态CoCrW合金的低。铸态与热压态CoCrW合金的断裂方式分别为穿晶断裂和沿晶断裂,而磨损机制均为二体磨损。

The microstructures and mechanical properties of as-cast and vacuum hot-pressed CoCrW alloys were studied by means of SEM, TEM, XRD, room temperature tensile test and ball-on-disc reciprocating wear test. The results show that the as- cast CoCrW alloy consists of three phases of y-Co, M12C, and M23C6, and the hot-pressed CoCrW alloy is composed of four phases of y-Co,CrCo, M12C, and M23C6. There are prior particle boundaries and cavities formed by rigid particles in the hot pressed CoCrW alloy, which reduces the mechanical properties of hot pressed CoCrW alloy.The ultimate tensile strength and elongation of as-cast CoCrW alloy is superior to that of hot press CoCrW alloy, but the hardness and wear resistance of as-cast CoCrW alloy is inferior to that of hot-pressed CoCrW alloy. The fracture mechanisms of as-cast CoCrW alloy and hot-pressed CoCrW alloy are the transgranular fracture and intergranular fractureres, pectively, and their wear mechanisms are both two-body abrasion.