Mo含量对粉末烧结Ti-6Al-4V-2Cr合金组织和力学性能的影响

Effects of Mo Addition on Microstructure and Mechanical Properties of Powder Metallurgical Ti-6Al-4V-2Cr Alloy

采用冷等静压+真空烧结(CIP)法制备了不同Mo含量的Ti-6Al-4V-2Cr合金,并对其进行了组织和力学性能分析。结果发现,不同Mo含量下钛合金的致密度基本都达到98%,且当Mo含量为1.5%时,更为致密;当Mo含量低于1.5%时,合金的组织为等轴晶组织,且随Mo含量增加,晶粒变小;当Mo含量高于1.5%时,组织为网状组织;合金的强度、硬度(HV)和伸长率在Mo含量为1.5%时达到最大值,分别为1 054.7 MPa、332.7、6.1%;经过物相分析,钛合金的主要相组成为α相和β相,但在透射电镜下观察发现,当Mn含量为3.0%时,Ti-6Al-4V-2Cr合金显微组织中出现硬脆的TiCr_2相,会降低合金的力学性能。

Titanium alloy of Ti-6Al-4V-2Cr contained different Mo was prepared by the cold isostatic pressing and vacuum sintering.Effects of varied Mo content on microstructure and mechanical properties of the alloy were investigated by OM,XRD and SEM,tensile testing.The results show that the relative density of the alloy with different Mo content reaches over 98%,and it is the most dense with the Mo content of 1.5%.The microstructure of the alloy is varied with different Mo content.When the Mo content is less than 1.5%,the morphology of the alloy consists of coarse equiaxed grains,and they will be refined gradually along with the increase of Mo content.However,when the Mo content is more than1.5%,the morphology shows basket-weave shape.The tensile strength,hardness and elongation of the alloy are increased firstly and then decreased with the increase of Mo content,where they reach 1 054.7MPa、332.7HV、6.1%,respectively,with 1.5% Mo addition.Titanium alloy mainly consists ofα-Ti andβ-Ti phase through the X-ray diffraction（XRD）,and the hard brittle TiCr2 phase can be observed in the microstructure of Ti-6Al-4V-2Cr alloy containing 3.0% Mo,which can reduce the mechanical properties of alloy.