摘要
采用激光选区熔化(Selective Laser Melting,SLM)技术制备TC4钛合金蜂窝状拓扑结构预制体,利用真空压力浸渗将7075铝合金熔体浸渗入其中,得到7075/TC4复合材料。研究表明:复合材料密度为3.65 g/cm3,7075铝合金区域主要由fcc-Al、Al3Fe和MgZn2组成;TC4钛合金区域组织对浸渗温度不敏感,均由片条状的α相和β相组成。7075铝合金区域与TC4钛合金区域的界面处产生了Al3Ti化合物界面层,界面层厚度在浸渗温度700、750和800℃时分别约为6、16和300μm。浸渗温度为750℃时,复合材料力学性能最佳,其屈服强度、抗压强度和塑性分别为(755±5)MPa,(1 136±12)MPa和23%±1.5%。加载时裂纹容易萌生于铝合金区域的晶界第二相、界面和孔洞等缺陷处。
With the rapid development of aerospace and rail transit,single metal material is difficult to meet the requirements of light weight and high strength.Heterogeneous composite materials combined with two or more metal materials can obtain a good combination of strength and toughness.7075 aluminum alloy has high strength and low density,and TC4 titanium alloy is the most widely used titanium alloy with both strength and toughness.Therefore,7075 aluminum alloy and TC4 titanium alloy are combined to obtain bimetallic composites with excel‐lent properties.In this paper,TC4 titanium alloy honeycomb topological structure preform was prepared by Selec‐tive Laser Melting technology,and 7075 aluminum alloy melt was infiltrated at 700/750/800°C by vacuum pres‐sure infiltration to obtain 7075/TC4 composites.The area of 7075 aluminum alloy in 7075/TC4 composites is main‐ly composed of fcc-Al,Al3Fe and MgZn2.The region of TC4 titanium alloy is mainly composed of lamellarαphase andβphase.The interface layer is mainly composed of Al3Ti,and its thickness increases from 6μm at 700°C to about 300μm at 800°C.When the infiltration temperature is 750°C,the properties of the composites are the best,and the yield strength,compressive strength and fracture strain are(755±5)MPa,(1136±12)MPa and 23%±1.5%,respectively.The fracture behavior of the composite material is as follows:the crack initiates at the grain boundary of the aluminum alloy region.With the increase of load,the cracks in the aluminum alloy area expand,and the cracks initiate at the defects of the interface and the titanium alloy area.With the further increase of the load,the cracks in the aluminum alloy region expand to the interface,and connect with the cracks in the interface and the ti‐tanium alloy structure region,resulting in material failure.At different infiltration temperatures,the phase composi‐tion of the composite 7075 aluminum alloy region,TC4 titanium alloy region and interface region is similar.How‐ever,the thickness of the interface layer increases with the increase of infiltration temperature.With the increase of infiltration temperature,the compressive strength and compressive plasticity of the composites first increase and then decrease,and reach the best at 750°C.The grain boundary second phase,infiltration defects and SLM defects have adverse effects on the properties of the composites.
作者
董志燕
赵海东
杨超
张卫文
王智
DONG Zhiyan;ZHAO Haidong;YANG Chao;ZHANG Weiwen;WANG Zhi(National Engineering Research Center for Near-Net-Shape Forming of Metallic Materials,South China University of Technology,Guangzhou 510640,China)
出处
《粉末冶金工业》
CAS
北大核心
2023年第4期7-14,共8页
Powder Metallurgy Industry
基金
国家重点研发计划资助项目(2020YFB2008300,2020YFB2008301,2020YFB2008305)
高端外国专家引进计划资助项目(G2021163004L)
广东省国际科技合作领域粤港澳大湾区国际科技创新中心建设基金资助项目(2021A0505050002)。
