Effect of Si content on surface hardening of Al–Si alloy by shot peening treatment

The effect of Si content was investigated for Al–Si alloys (Al-7%, 11%, 18%Si) by shot peening process. The hardness increment by shot peening increased as the Si contents in Al–Si alloys increased. Finer Si particles and more dense distribution of those were observed in Al–18%Si than Al–7%Si. As Si contents of Al–Si alloys increased, grain size at the surface area of Al–Si alloy decreased. Higher hardness of Al–Si alloy with higher Si content could be attributable to more dense and refine Si particles and accelerated grain refinement during severe deformation.

► Shot peening process was applied onto the surface of Al–Si alloy with various Si contents (7, 11, 18%).
► Higher surface hardness was attained as Si content increase in Al–Si alloy.
► Severe plastic deformation induced more refined Si particle and nano-sized grains at the surface of Al–Si with higher Si content.
► More refined Si particles, densely distributed, and finer nano-grains lead to higher hardness in Al–Si alloy with higher Si content.