Effect of Solutionising on Change in Phase Morphology, Mechanical Behavior & Corrosion Behavior for AZ Series as Cast Automotive Magnesium Alloy Components

Magnesium is sought to be one of the futuristic material in automotive due to its superior properties such as density, strength to weight ratio, damping characteristics and thus, making it a key enabler for light weighting. The properties of Magnesium alloys can be widely altered by change in elemental composition and heat treatment. Analysis of composition and phase morphology are driving factors for determining component’s end use properties and can be utilized effectively in its product development cycle. The as-cast AZ series alloys develop microstructure consisting of α-Mg matrix, eutectic α-Mg/γ-Mg₁₇Al₁₂ phase with non-uniform Al solute content in the α-Mg. Solutionising causes dissolution of Mg₁₇Al₁₂ brittle phase thereby increasing strength and ductility in these alloys. This paper presents analysis of AZ series automotive alloy components with focus on microstructure and mechanical properties change after solutionising. Scanning electron microscopy & energy dispersive spectroscopy techniques are adopted to evaluate phase changes along with morphology which affected properties after solutionising. Corrosion behaviour of AZ91 in as cast, solutionized and solutionized & aged condition is also studied.