Effect of strontium on the microstructure and mechanical properties of aluminium ADC12/Nano-SiC composite with Al-5TiB grain refiner by stir casting method

The effects of Sr addition on mechanical properties and microstructure of aluminium ADC12/Nano-SiC composites produced by stir casting have been investigated. The addition of Sr into ADC12 matrix was varied from 0.01 to 0.03 wt% and the other elements added were Al-5TiB as a grain refiner and Mg as a wetting agent. It was found that the phases present in composites analysed by Scanning Electron Microscope link to Energy Dispersive Spectra was Mg ₂ Si primary, Mg ₂ Si binary, β-Al ₅ FeSi and Al ₂ Cu respectively. The results show that Sr modifies acicular/plate like of Al-Si eutectic into fibrous. Sr also reduced slightly the average size of blocky Mg ₂ Si primary and changed Chinese script of Mg ₂ Si binary into polyhedral or finer fibrous shape. The modification effect plays role in improving mechanical properties. The highest optimum UTS and elongation were obtained at composites with 0.025 wt% Sr with the value of 292 MPa and 1.88% respectively, while the SDAS was 11.85 μm. The hardness and wear rate of all composites were relatively no changed.