Effect of Heat Treatment on the Microstructure and Properties of Ni-Si-B Alloy by Laser Additive Manufacturing

Ni-Si-B samples were prepared by a laser additive manufacturing method, and three heat treatments were performed to study their effect on the microstructure and mechanical properties of the samples. The microstructure of the as-deposited sample was mainly composed of γ-Ni and Ni3Si. After solution treatment, the crystal grains coarsened and the wear resistance was the worst. The wear resistance of the samples after heat treatment showed varying degrees of deterioration at 25 and 200 °C. After solution plus aging treatment, the dispersed Ni3Si strengthening phase precipitated in the matrix, thereby increasing the dislocation energy in the matrix. Compared with the solution-treated samples, the wear resistance significantly improved. The wear mechanism is mainly adhesive and abrasive wear. The impact toughness of the sample after solution treatment decreased to 3.64 J/cm2. The grain refinement and strengthening conferred by Ni3Si precipitated in the matrix help to improve the impact toughness of the samples.