后处理对电子束熔化成形Ti48Al2Cr2Nb合金组织及性能的影响

Effect of post-treatment on microstructure and properties of Ti48Al2Cr2Nb alloy prepared by electron beam melting

采用电子束熔化成形(EBM)技术制备了Ti48Al2Cr2Nb合金试棒,并对其进行后处理。采用X射线衍射仪(XRD)、扫描电镜(SEM)、显微硬度计及万能材料试验机等研究了未处理、热等静压(HIP)及热处理后合金的显微组织及力学性能。结果表明:EBM制备的Ti48Al2Cr2Nb合金组织以γ相和α_(2)相为主。热等静压处理后,合金的致密度由3.1441 g/cm^(3)增加至3.5343 g/cm^(3),显微硬度由257 HV0.1增加至315 HV0.1。热处理后,合金的晶粒发生明显长大,随着保温温度由1220℃升高至1280℃,等轴γ组织的体积分数由50.12%降低至19.37%。热处理后合金的拉伸强度相较于未处理试样(403 MPa)均有一定下降,1260℃保温120 min后合金的拉伸强度降低至268 MPa。

Ti48Al2Cr2Nb alloy bars were prepared by using electron beam melting(EBM)technology and subjected to post-treatment.Microstructure and mechanical properties of untreated,hot isostatic pressing(HIP)treated and heat treated alloy were studied by means of X-ray diffraction(XRD),scanning electron microscopy(SEM),microhardness tester and universal material testing machine.The results show that the microstructure of the Ti48Al2Cr2Nb alloy prepared by EBM is dominated byγandα_(2)phases.After hot isostatic pressing treatment,the density of the alloy increases from 3.1441 g/cm^(3)to 3.5343 g/cm^(3),and the microhardness increases from 257 HV0.1 to 315 HV0.1.After heat treatment,the grains of the alloy grow obviously,and as the holding temperature increases from 1220℃to 1280℃,the volume fraction of equiaxedγstructure decreases from 50.12%to 19.37%.After heat treatment,the tensile strength of the alloy decreases to a certain extent compared to the untreated sample(403 MPa),and becomes into 268 MPa after holding at 1260℃for 120 min.