THEORETICAL ANALYSES ON TENSILE STRENGTH OF ZA22/Al₂O₃ SHORT FIBER COMPOSITES AT ELEVATED TEMPERATURE

The tensile strength of squeeze casting ZA22/Al₂O₃ short fiber composites at elevated temperature was measured with autograph AG 10TA universal testing machines made in Japan. The experimental results were analyzed by means of the rule of mixture (ROM) model modified by Friend. The results show that the tensile strength of ZA22 alloy and ZA22/Al₂O₃ short fiber composites decreases with the increasing temperature, but the decreasing rate of the tensile strength of ZA22 alloy is larger than that of ZA22/Al₂O₃ short fiber composites. There is a critical temperature T crit for any composites with a fiber volume fraction. The tensile strength of the composites is higher than that of matrix if the temperature is above T crit . The more the fiber volume fraction is, the lower the critical temperature T crit . T crit of the composites with 15% and 20% fiber volume fraction are 123℃ and 87℃, respectively. There is a critical fiber volume fraction V crit under a temperature. The tensile strength of the composites is higher than that of matrix if V f is above V crit . The higher the temperature, the lower the critical fiber volume fraction. For ZA22/Al₂O₃ short fiber composites, the value of the empirical parameter C * in Friend model decreases with the increasing temperature.