激光选区熔化Cr3C2/CoCrMo合金的组织结构及力学性能研究

Microstructure and Mechanical Properties of Cr3C2/CoCrMo Alloy Prepared by Selective Laser Melting

摘要:

通过激光选区熔化(SLM)技术制备了高致密度的CoCrMo和Cr3C2/CoCrMo合金，对比研究CoCrMo和Cr3C2/CoCrMo合金的组织结构、拉伸性能及磨损性能，探讨添加Cr3C2颗粒对CoCrMo合金组织及性能的影响机制。研究发现，合金的主要组成相为γ-Co和ε-Co，添加Cr3C2使合金的物相发生改变，产生M23C6相。CoCrMo与Cr3C2/CoCrMo合金的组织均由外延生长的柱状晶和等轴晶组成，添加Cr3C2使柱状晶数量减少。Cr3C2/CoCrMo合金的硬度为514±18 HV，抗拉强度为1520 MPa，相比于CoCrMo合金分别提升了27%、39%。在相同载荷下，Cr3C2/CoCrMo合金的磨损量明显小于CoCrMo合金，耐磨性能提升30%。在SLM过程中，添加的Cr3C2颗粒快速熔解，Cr固溶在基体中，产生固溶强化；在晶界处转变生成M23C6型碳化物，具有沉淀强化作用，有效提高了合金的强度和耐磨性。

Abstract:

In this study, high-density CoCrMo and Cr3C2/CoCrMo alloys were prepared by selective laser melting (SLM) to investigate the effect of Cr3C2 particles on the microstructure, strength and wear resistance of the CoCrMo alloys. It was found that the phases of the alloy were γ-Co and ε-Co, and the M23C6 phase was generated due to the addition of Cr3C2. The organization of both CoCrMo and Cr3C2/CoCrMo alloys consisted of epitaxial columnar crystals and homogeneous cellular crystals, and the addition of Cr3C2 reduces the number of columnar crystals. The mechanical characteristics of specimens were tested through experiments, Cr3C2/CoCrMo specimens have a hardness of 514±18 HV and an ultimate tensile strength of 1520 MPa, an increase of 27 % and 39 % respectively compared to CoCrMo specimens. Under the same load, Cr3C2/CoCrMo alloy demonstrates superior wear resistance and less wear loss than CoCrMo alloy, and the wear resistance is improved by 30%. During the SLM process, the added Cr3C2 particles melt rapidly, Cr generates a solid solution strengthening in the matrix; Cr3C2 transforms at the grain boundaries to generate M23C6-type carbides with precipitation strengthening, improving the strength and wear resistance of the alloy.