【摘要】 电子束选区熔化具有高能量利用率、高真空环境及粉末床能预热至1000℃以上等特点,可有效避免钛铝合金出现裂纹和氧化现象。但电子束选区熔化会产生元素挥发,严重时会改变合金粉末的元素成分,最终影响合金零件的组织和性能。基于电子束扫描线能量密度对电子束选区熔化工艺中Ti47Al2Cr2Nb合金铝元素的挥发及其抑制进行了研究和探讨。结果表明:当电子束线能量密度从1680 J/m增加到2880 J/m时,制备试样的铝元素原子比例从43%逐渐减小到35%,随后又变大到37%;当电子束线能量密度为2160、2400 J/m时,电子束选区熔化试样的显微组织出现等轴化倾向,变为椭圆状组织。为了减少铝元素的挥发,电子束选区熔化输入的线能量密度须控制在约1680 J/m。更多还原

【Abstract】 Electron beam selective melting has the advantages of high energy utilization and high vacuum environment,and its powder bed can be preheated to more than 1000 ℃,which can effectively avoid the cracks and oxidation of Ti Al alloy. However,electron beam selective melting could cause the evaporation of elements,which may change the element composition of the alloy,and eventually affects the microstructure and properties of the alloy. Based on the line energy density of electron beam scanning melting,the volatilization and inhibition of Ti47 Al2 Cr2 Nb alloy in the process of electron beam selective melting are studied and discussed. The results show that when the line energy density increases from 1680 J/m to 2880 J/m,the aluminum proportion of the built sample gradually decreases from 43% to 35%,and then increases to 37%. When the line energy densities are 2160 J/m and 2400 J/m,the microstructure of the electron beam selective melting specimen becomes elliptical microstructure. In order to reduce the volatilization of aluminum,the line energy density should be controlled at about 1680 J/m.更多还原