Study on the effect of pressure and cooling rate on the solidification Characteristics and mechanical properties of Al-11%Si cast alloy

The effect of various cooling rates which was achieved by means of squeeze casting samples on microstructure and solidification of al-11%si cast alloy has been investigated. investigations have been made by differential thermal analysis (dta) and metallographic analysis. for this purpose, the solidification process was studied using the cooling curve and crystallization curve at solidification rate ranging from 5 k/min up to 99 k/min. the results show that, during the solidification at different cooling rates, the undercooling and recalescence of primary and eutectic crystallization have been detected and related with largeness of primary crystals of α(al) and eutectic phase β(si) from eutectic (αal + βsi). increasing the cooling rate increases significantly the liquidus temperature, nucleation undercooling temperature, solidification range and decreases the undercooling temperature. therefore, increasing cooling rate refines all microstructural features including secondary dendrite arm spacing (sdas) intermetallic compounds thus improves mechanical properties.