Microstructure and thermal expansion behavior of spray-deposited Al–50Si

• The thermal expansion behavior of spray-deposited Al–50Si was investigated.
• The CTE for spray-deposited alloy is higher than the as-cast alloy.
• High solid solubility of Si(Al) promote the increasing of CTE.
• The formation of Al(Si) solid solution has a positive effect on decreasing of CTE.
• The measured CTE is in good agreement with the Turner model after 843 K HIP.

The evolution of microstructure and coefficient of thermal expansion (CTE) of the Al–50Si (wt.%) alloy manufactured by spray deposition followed by hot isostatic pressing (HIP) are systematically investigated. The results indicate that the microstructure of the deposited alloy is composed of primary Si with average size of 12.5 ± 0.1 μm and α-Al. The CTE of the deposited alloy is higher than the corresponding alloy produced by casting due to the high solid solubility of Al in Si. After HIP, the CTE is lower than the parent as-deposited alloy owing to the high solid solubility of Si in Al. The residual thermal stress results in a higher CTE during the second heating as a result of the CTE mismatch between the Al matrix and the primary Si particles. Furthermore, the measured CTE value is in good agreement with the Turner model after complete densification by HIP at 843 K.