Microstructure and shear fracture behavior of Mo/AlN/Mo symmetrical compositionally graded materials

The metallization of AlN ceramic is a critical prerequisite for applying AlN ceramics to electronic component packaging. In this study, a concept of functionally graded materials (FGMs) was used for the metallization of AlN ceramic. Symmetrical Mo/AlN/Mo FGMs with different composition exponent p (p=1, p1) were designed and fabricated by hot-press sintering. The influence of the p-value on the shear performance and fracture path of the Mo/AlN/Mo FGMs was investigated. Compared to specimens with p=1, the specimens with p1 show the distribution of Mo-rich and AlN-rich in the graded transition layer, respectively. The shear strength of the specimens reaches a maximum value of 48.0 MPa as p 1. Besides, three fracture paths were found for the Mo/AlN/Mo FGMs with different values of p, including the cracks propagate obliquely along the axis in the graded transition layer, the cracks penetrate through the AlN ceramic and the graded transition layer, and the cracks only propagate horizontally in a single graded layer. The crack initiation of Mo/AlN/Mo FGMs depends on the strength of each graded layer. Moreover, the directions of fracture paths are closely related to the strength of the ceramic interlayer and the composition exponent p.