Structure-mechanical property relationships of in-situ A356/Al3Zr composites

In this work, structure-mechanical property relationships of an in-situ A356/Al3Zr composite were investigated by means of experiments and microstructure based modeling. The composite was synthesized through an in-situ reaction of A356-K2ZrF6. It was evidenced by XRD analysis that the Al3Zr reinforcement was successfully formed in the cast composite material. Examinations of developed microstructures revealed that Al3Zr reinforced particles with a blocky shape were uniformly dispersed throughout the A356 matrix. The in-situ Al3Zr reinforced particles improved overall tensile strength, but deteriorated elongation of the A356/Al3Zr composite. Nevertheless, Sr modification reduced the size and aspect ratio of eutectic silicon that resulted in a simultaneous enhancement of the tensile strength and ductility. Local stress and strain distributions of the composites and interactions between their constitutive phases were studied in details by microstructure based FE models. Firstly, predicted stress-strain responses of all composite configurations were verified by comparing with respectively experimental tensile curves. Then, results from the microscopic FE simulations were discussed with regard to effects of different phases on occurrence of localized shear bands and possible crack sites.