冷喷连接镁铝异质接头组织与力学性能研究

传统焊接在铝合金异质连接工艺中存在缺陷，为避免铝合金异质连接接头中的脆性相以及低强度的问题，研究了冷喷连接镁铝异质金属接头的可行性。通过N2作为加速气体，在主气压力3.5 MPa、气体温度350 ℃、喷涂角度90°、走枪速度40 mm/s、喷涂距离20 mm、送粉速率2.5 r/min的最佳冷喷连接参数下，以球形纯铝粉末与球形不锈钢颗粒的混合粉末作为冷喷连接粉末，纯铝板与AZ91D镁合金板作为基体，制备了冷喷连接镁铝异质金属接头。系统研究了冷喷连接接头的硬度、拉伸强度、弯曲强度、剪切强度等力学性能，结果显示，冷喷镁铝接头的拉伸试样断裂在铝母材处，拉伸强度为105 MPa，正、背弯曲试样均断裂在沉积体与铝母材的结合界面，弯曲强度分别为226.7 MPa和316.7 MPa。研究表明，冷喷连接在以制铝合金连接过程中避免了合金的熔化，消除了传统焊接中脆性金属间化合物的生成，并且其连接强度不低于母材强度。

Analysis of Microstructure and Mechanical Properties of Mg-Al Joints by Cold Spray Bonding

Traditional welding has defects in the aluminum alloy heterogeneous bonding process. In order to avoid the brittle phase and low strength problems in the aluminum alloy heterogeneous joints, the feasibility of cold spray bonding the magnesium-aluminum heterogeneous alloy joints is studied. By using N2 as accelerating gas, the main gas pressure is 3.5 MPa, the gas temperature is 350 ℃, the spraying angle is 90°, the nozzle speed is 40 mm/s, the spraying distance is 20 mm, and the powder feeding rate is 2.5 r/min. Under this best cold spray bonding parameters, the mixed powder of spherical pure aluminum powder and spherical stainless steel particles is used as the cold spray powder, the pure aluminum and the AZ91D magnesium alloy are used as the substrate to prepare the cold spray bonding of the magnesium-aluminum heterogeneous alloy joints. The mechanical properties of the cold-sprayed joints such as hardness, tensile strength, bending strength, and shear strength have been systematically studied. The results show that the tensile specimen of cold sprayed magnesium-aluminum joint breaks at the aluminum base metal and the tensile strength is 105 MPa. Both the front and back bending specimens fractured at the bonding interface between the deposit and the aluminum substrate, and the bending strength was 226.7 MPa and 316.7 MPa respectively. The research show that the cold spray joints avoids the melting of the alloy during the bonding process of the aluminum alloy, eliminates the formation of brittle intermetallic compounds in traditional welding, and its bonding strength is not lower than the strength of the base metal.