Microstructure and mechanical behavior of Al–Mg/Ni–P composites

Abstract

The microstructure and mechanical behavior of electroless deposited Ni–P on Al–Mg substrates were investigated. The microstructures of the as-deposited and annealed samples were characterized through optical and scanning electron microscopy. Hardness measurements were made both on the Al–Mg substrate and the Ni–P coating using a depth sensing hardness machine. The plastic deformation behavior of the composites was studied and the results show that the initial deformation is accompanied by the appearance of serrations on load-displacement curves. Decohesion of the hard Ni–P takes place at large strains. An estimate of the ultimate shear strength of the Al–Mg/Ni–P interface was made and the strength of the interface was determined to be −0.45 GPa. The tribological properties of the amorphous Ni–P were studied using ball-on-disk and slider-on-disk tests. In particular, the influences of humidity, surface roughness, and heat treatment on friction and durability of the coatings were investigated.