Effect of temperature on the mechanical behaviour of magnesium alloy AZ91D in the range between -30 degree C and 250 degree C

• Published in: International journal of mechanical sciences 2014-09, Vol.86, p.34-45
• Main Authors: Ahmad, IR, Jing, Xiao, Shu, D W
• Format: Article
• Language: English
• Subjects: Alloy systems; Aluminum; Cracks; Magnesium; Magnesium base alloys; Mechanical properties; Softening; Strain rate
• ISSN: 0020-7403
• DOI: 10.1016/j.ijmecsci.2014.04.010

The temperature effect on the behaviour of magnesium alloy AZ91D is investigated. The temperature is varied between -30 degree C to 250 degree C. It is observed that the effect of temperature on the mechanical behaviour of the alloy under tension is dissimilar to compression. Under tensile loading, the effect of temperature is little at quasi-static strain rate while significant at 1500s-1. On the other hand the effect of temperature is considerable at quasi-static strain rate while little at 2500s-1. Thermal softening, voids and cracks in beta -phase and favourable orientation of crystals in the direction of tensile loading are responsible for reduced tensile stress at 1500s-1 strain rate and 250 degree C temperature. Microstructure analysis reveals that at elevated temperature additional slip systems are activated causing the stress of the alloy to decrease and ductility to increase. Furthermore, the hard and brittle intermetallic beta -Mg17Al12 decomposes into aluminium and magnesium giving rise to the nucleation of micro-cracks at the interface between beta -phase and the magnesium-matrix causing detrimental effect on the mechanical properties of the alloy.