激光增材制造(Ti+B4C)/AA7075铝合金工艺与组织性能研究

Microstructure and properties of (Ti+B4C)/AA7075 composite powder laser melting and deposition

摘要:

通过高能球磨法制备了加入5 wt.%的球形纯钛粉和不同含量B4C陶瓷颗粒（3 wt.%，5 wt.%，10 wt.%）的(Ti+B4C)/AA7075复合粉末，采用激光熔化沉积技术（Laser Melting Deposition，LMD）制备了多组增材试样，研究了钛元素以及不同质量分数B4C陶瓷粉末对复合材料显微组织和力学性能的影响规律。结果表明：同时添加球形纯钛粉以及B4C陶瓷颗粒可以有效解决7075铝合金在LMD成型过程中出现的气孔与开裂问题。当B4C的质量分数为3 wt.%时，复合材料的平均显微硬度以及抗拉强度分别为141.65 HV0.2和336.93 MPa，比沉积态7075铝合金的100.07 HV0.2和200.05 MPa分别提高了41.5 %和68.4 %。之后，随着B4C质量分数由3 wt.%增加到10 wt.%，试样的抗拉强度逐渐降低，但耐磨性能逐渐增强，平均摩擦系数由0.83降到0.78，磨损形式由黏着磨损转变为剥层磨损。

Abstract:

The (Ti + B4C) / AA7075 composite powder with 5 wt.% and B4C ceramic particles (3 wt.%, 5 wt.%, 10 wt.%) was prepared by high-energy ball grinding, and several groups of additive samples were prepared by laser melting deposition technology (Laser Melting Deposition, LMD). The influence of titanium elements and different mass fractions B4C ceramic powder on the microscopic organization and mechanical properties of the composite materials was studied. The results show that the addition of spherical pure titanium powder and B4C ceramic particles can effectively solve the stoma and cracking problems of 7075 aluminum alloy during LMD molding process. When the mass fraction of B4C was 3 wt.%, the average microhardness and tensile strength of the composite were 141.65 HV 0.2 and 336.93 MPa, respectively, which were 41.5 % and 68.4 % higher than 100.07 HV 0.2 and 200.05 MPa of the deposited 7075 aluminum alloy. Later, with the increase of B4C mass score from 3 wt.% to 10 wt.%, the tensile strength of the sample gradually decreased, but the wear resistance gradually increased, the average friction coefficient decreased from 0.83 to 0.78, and the wear form changed from adhesive wear to peeling wear.