Microstructure evolution mechanism and mechanical properties of AlNP/Al composites bonded to 6061Al at low temperature

In order to prevent the damage of the connected electronic components at high temperature and improve the wettability of the commonly used low-temperature SnAgCu(SAC) solder on the surface of the base material 25%AlNP/Al(volume fraction) composite and 6061Al alloy, the Ni thin layer or the Ti/Ni bimetal thin layer on the surface of the base metal were pre-metallized by magnetron sputtering, and then connected with a SnAgCu solder, a well-bonded joints was obtained. After double metallization, the interface on both sides of the joint is composed of base material /Ti-Al/Ti/Ti-Ni/Ni/Ni-Sn-Cu/β-Sn+Ag3Sn. The difference in diffusion speed between different elements leads to differences in the phase composition of the interface reaction layer at different positions. From the Ni plating layer to the center of the weld, the phase of the reaction layer is (Ni,Cu)3Sn, (Ni,Cu)3Sn2, (Ni,Cu)6Sn5, (Ni,Cu)3Sn4. The addition of Ti element can significantly improve the bonding strength between the Ni-plated layer and the base metal. The joint shear strength of the joint material obtained by brazing the base metal after double metallization at 250 ℃ for 1 min to 5 min can reach 28-35 MPa, fracture occurs at β-Sn matrix.