Effect of Ni on microstructure and hardness of Al- 15%Mg2Si metal matrix composite

The excellent properties of Al-Mg2Si composites can be seriously affected by the coarse Mg2Si particles and brittle eutectic matrix. Undesired structure of the composite, specially the presence of large Mg2Si particles in as-cast condition, will lead to undesirable characteristics of the composites. In this work effort was made to study the effect of Ni on microstructure and hardness of Al-15%Mg2Si composite which was produced by an in-situ casting method. Microstructural studies were done by optical and scanning electron microscopy. The results showed that with increasing Ni content, Al-Mg2Si binary eutectic structure gradually evolves into Al-Mg2Si-NiAl3 ternary eutectic. The addition of 0.1–5 wt.% Ni to the composite, also increased its hardness from 101 HB to 136 HB, which is equivalent to 35% enhancement in hardness results.

Keywords:

Al-Mg2Si composite , Ni addition , Microstructure , Mechanical properties