Effect of Cooling Rates and Heat Treatment on the Structure and Properties of Al-8Ca

On account the research of casting Al-8 Ca is not through at present,the Al-8 Ca(mass fraction/%)alloy ingots are prepared by two casting processes namely copper-cooled and metal-cooled in the cooling rate of 10~2 K/s and 25 K/s.The structure of these two types of Al-8 Ca are improved by granular process,and the effects of different cooling rates and heat treatments on the structure and tensile property of Al-8 Ca are studied. The results show that the structure of these two types of Al-8 Ca are α-Al and Al_4 Ca,the alloy of the 10~2 K/s has smaller structure and the Al_4 Ca is distributed evenly; the Al_4 Ca of these two types of Al-8 Ca alloy are grow, swallow each other and reduce in 550℃ over time,and the alloy of 10~2 K/s has smaller and more granular particles; compared with the alloy of 25 K/s,the tensile strength of 10~2 K/s is increased from 196 MPa to 386 MPa and the elongation rate increased from 4.91% to 8.19%;the elongation and tensile strength of optimal heat treatment status of 10~2 K/s are increased from 8.19% to 13.91% and decreased from 386 MPa to 358 MPa,and the elongation and tensile strength of optimal heat treatment status of 25 K/s are increased from 4.91% to 6.75% and decreased from 196 MPa to 177 MPa.It is observed that increasing the cooling rate of the melt,the Al-8 Ca alloy of microstructure are effective optimize and tensile property are improve.