Microstructural and Mechanical Properties of A356/Ni Alloys Produced by the Mechanochemical Method

Abstract

In this study, A356 powder was alloyed with elemental Nickel (Ni) powder in different ratios using a mechanochemical alloying method. Alloyed A356/XNi powders were cold pressed along one axis under a load of 350 MPa and sintered at 600°C. To determine the effect of intermetallic phases formed on the microstructure in proportion to the amount of Ni, the A356/XNi alloys were characterized by X-ray diffraction (XRD) analysis, density, and microhardness values. As a result, after mechanical alloying, the spherical microstructure of the A356 alloy turned into a spongy form due to the sponge-like Ni elemental powders. After sintering, it was determined by optical microscopy and scanning electron microscopy (SEM) examinations that the grain size of A356/XNi alloys increased with an increasing amount of Ni. In addition, it was determined that the relative density and amount of porosity increased with an increasing amount of Ni. According to the XRD analysis results, it was determined that AlNi, Al₃Ni₂, Al₃Ni and AlFeNi intermetallic phases formed in the microstructure due to the mechanochemical and sintering process.