Improved properties of Al matrix composites reinforced with Ni-coated β-Si3N4 whiskers

In order to enhance the interfacial bonding between aluminum and β-Si3N4 whiskers in Al matrix composites (AMCs), Ni coating was deposited on the surface of β-Si3N4 whiskers using an electroless plating method. The interfacial test results showed that Ni coating was successfully deposited on the surface of β-Si3N4 whiskers and the whiskers were well bonded with Al matrix without pores. In addition, the whiskers were homogeneously dispersed in the Al matrix. The effect of Ni-coated β-Si3N4 whiskers on the mechanical properties of composites was investigated in detail. Densification and the mechanical performance of AMCs reinforced by Ni coated β-Si3N4 whiskers (NSAMCs) were improved comparing to that of AMCs reinforced by uncoated β-Si3N4 whiskers (USAMCs). The maximum value of tensile strength and bending strength reached up to 290 MPa and 487 MPa, when the Ni content was 0.9 vol.% and the β-Si3N4 whiskers content was 20 wt.%, respectively. However, excessive Ni content weakened the strengthening effect. Medium Ni coating on β-Si3N4 whiskers significantly optimized the interface and improved the performance of the composites.