A new intermetallic phase formation in Mg-Si-Ni magnesium-based in-situ formed alloys

The effects of nickel addition on the microstructure and phase formation in the magnesium-silicon alloy were studied. Besides the primary and eutectic in-situ formed Mg2Si phase in the Mg-Si alloys, a new intermetallic phase was identified in the Ni-containing alloys. Based on energy-dispersive spectroscopy (EDS) and X-ray diffraction analyses, it was shown that this phase contains Mg, Ni, and Si elements, which contradicts the presence of the expected Mg2Ni phase. Through rigorous EDS analysis, the new in-situ formed phase was identified as (Mg,Ni)(3)Si or more accurately as Mg8Ni7Si5 intermetallic compound, called chi-phase, which has not been reported so far in the Mg-Si-Ni ternary space. Finally, the properties of the studied Mg-Si-Ni alloys were also briefly discussed.