(TiH2+TiB2)/AA7075复合粉末激光选区熔化成形的显微组织与力学性能  

Microstructure and mechanical properties of selective laser melting of(TiH2+TiB2)/AA7075 composite powders

作　　者：欧阳盛 刘允中[1] 沈君剑 肖小军 OUYANG Sheng;LIU Yunzhong;SHEN Junjian;XIAO Xiaojun(National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials,South China University of Technology,Guangzhou 510640,China)

机构地区：[1]华南理工大学国家金属材料近净成形工程技术研究中心,广州510640

出　　处：《粉末冶金材料科学与工程》2020年第3期197-205,共9页Materials Science and Engineering of Powder Metallurgy

基　　金：广东省重点领域研发计划资助项目(2019B090907001);广东省科技计划资助项目(2014B010129002,2016B090913001)。

摘　　要：在AA7075合金粉末中加入0.6%~1.4%亚微米TiH2和0.8%纳米TiB2颗粒(均为质量分数,下同),采用低能球磨法制备(TiH2+TiB2)/AA7075复合粉末,再通过激光选区熔化成形(selective laser melting,SLM)制备(Ti+TiB2)/AA7075复合材料,研究TiH2添加量对复合材料显微组织与力学性能的影响。结果表明:亚微米TiH2和纳米TiB2颗粒的加入能显著抑制SLM成形AA7075合金的裂纹,添加1.4%TiH2+0.8%TiB2可使裂纹完全消除。随TiH2添加量由0.6%增加至1.4%,显微组织中的柱状晶全部转变为等轴晶,平均晶粒尺寸由2.33μm细化至1.38μm。TiH2添加量为1.4%的复合材料,抗拉强度和屈服强度分别为360 MPa和328 MPa,伸长率为12.0%。经T6热处理后,性能进一步提升,抗拉强度和屈服强度分别提高到461 MPa和394 MPa,伸长率增加至15.3%。0.6%−1.4%submicron TiH2 and 0.8%nano-TiB2 particles(mass fraction,the same as below)were added into AA7075 powders,low-energy ball milled(TiH2+TiB2)/AA7075 composite powders were used to fabricate composites by selective laser melting(SLM).Microstructures and mechanical properties of SLMed composites with different TiH2 additive amounts were studied.The results show that the addition of submicron TiH2 and nano-TiB2 particles can significantly inhibit the cracks of SLMed AA7075 composites.The cracks can be completely eliminated when 1.4%TiH2 and 0.8%TiB2 are added.When the TiH2 additive amount increases from 0.6%to 1.4%,columnar grains in the microstructure are all transformed into equiaxed grains,and the average grain size is refined to 1.38μm from 2.33μm.When the TiH2 additive amount is 1.4%,the tensile strength,yield strength and elongation of the AA7075 composites are 360 MPa,328 MPa and 12.0%,respectively.After T6 heat treatment,the properties are further improved.The tensile strength and yield strength increase to 461 MPa and 394 MPa,respectively,and the elongation increases to 15.3%.

关 键 词：7075铝合金 TiH2 TIB2 激光选区熔化 显微组织 力学性能 

分 类 号：TG146.21[一般工业技术—材料科学与工程]