ELEVATED-TEMPERATURE MECHANICAL-PROPERTIES OF SILICON-CARBIDE-WHISKER-REINFORCED ALUMINUM MATRIX COMPOSITES

The aging characteristics, elevated-temperature strength and stiffness as well as creep deformation of aluminum alloy 6061 composites reinforced with silicon carbide (SiC) whiskers (V(f) = 0.20) have been studied. The peak hardness for this composite was 148 kgf mm-2 after aging for 18 h at 150-degrees-C and 138 kgf mm-2 after aging for 1 h at 200-degrees-C following solutionization for 15 min at 530-degrees-C. The maximum tensile strength was retained after aging for 18-55 h at 150-degrees-C, an improvement of 40% over that of wrought aluminum. The tensile strength of the received composite decreases from 578 MPa at room temperature to 229 MPa at 350-degrees-C. In terms of the use temperature, the composite provides an advantage of approximately 200-degrees-C over that of wrought aluminum. Young's modulus for the composite remains almost constant (104 GPa) from 150 to 350-degrees-C, and it is 58% higher than that of the wrought aluminum at 150-degrees-C. Experimentally determined values of the steady state creep rate range from 4.9 X 10(-9) to 1.3 X 10(-6) s-1 for the composite which shows substantial resistance to creep deformation with respect to the wrought aluminum alloy. The activation energy and stress exponent for the composite are reported and discussed.