Effect of extrusion on the thermal expansion behavior of Al₁₈B₄O₃₃ whisker-Mg composites

The thermal expansion behaviors of AZ91D alloy and Al₁₈B₄O₃₃ whisker (w)-AZ91D fabricated by different techniques were investigated at 30-300 °C. The results indicate that these behaviors were greatly influenced by extrusion forming, which reduced the coefficients of thermal expansion (CTE) of AZ91D and Al₁₈B₄O₃₃w-AZ91D and resulted in negative strain. The residual stresses could be eliminated by thermal cycling. The CTE of the whisker-reinforced composites could be predicted accurately by micromechanical modelling.