Microstructure and mechanical properties of ZA27 based SiC reinforced composite processed by multi directional forging

Abstract

Influence of multi directional forging (MDF) on microstructural and mechanical properties of ZA27/SiC 5 weight percentage (Wt%) composites were investigated. Stir casting technique followed by squeezing process was adopted for synthesis of composite. MDF process was conducted at 100 °C and 200 °C upto strain of 0.54 and 1.09 respectively. Microstructure analysis was carried out using optical microscopy, scanning electron microscopy and energy dispersive spectrometry. SiC particles were fairly distributed and some clusters were also observed. Density of composite decreased with the reinforcement of SiC particles as compared with ZA27 alloy, however porosity which was existing as casting defect was reduced by MDF process. Average grain size of 200–250 nm and 1 μm was achieved for MDF processed sample at 100 °C upto 3 passes and at 200 °C upto 6 passes respectively. Addition of SiC particles and adoption of MDF technique improved the vickers hardness of composites. Ultimate tensile strength of ZA/SiC composite has increased from 380 MPa to 395 and 432 MPa respectively with 54 and 37 percentage of elongation to failure. Improvement in hardness and tensile strength is due to strain hardening and grain refinement. Ductility of MDF processed ZA27/SiC composite is attributed to uniform distribution of ultrafine equiaxed grain and micro constituents.