Effect of heat treatment on electrical resistivity and tensile strength of Al-0.35mass%Zr-0.15mass%Fe-XSi (X = 0.05-0.15mass%) wire rods produced by Properzi continuous casting and rolling (PCCR) process were studied, and the microstructure was observed by transmission electron microscopy. Solute Zr and Fe concentrations in wire rods of various Si content were analysed before and after a heat treatment. In as PCCR state, solute Zr concentration, C
Zr, was decreased by 0.15%Si addition. After an isothermal treatment, C
Zr decreases with increasing content of Si. The addition of 0.10%Si accelerates the precipitation of Zr and enhances age hardening, while that of 0.15%Si shortens the time to over age softening. Though solute Fe concentration, C
Fe, becomes to almost equilibrium concentration of Al-Fe binary alloy at 723K, supersaturation of solute Zr is maintained even after isothermal treatment at 723K for 180ks. As the heating rate decreases, the reduction of tensile strength by recovery in an early stage of isothermal treatment decreases, and the maximum tensile strength increases due to age hardening, suggesting nucleation of β'-Al
3Zr during heating.
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