Al_2O_3,Al_3Zr颗粒增强Al-12%Si基原位复合材料的高温热膨胀性

High-temperature thermal expansion properties of Al_2O_3,Al_3Zr particulate reinforced Al-12%Si in situ matrix composites

以Al-12%Si和Zr(CO3)2作为反应组元,通过原位反应法制备出Al2O3,Al3Zr颗粒增强铝硅基复合材料,通过快速凝固成型得到铸态试样.用热膨胀仪测试了材料在50～500℃范围内的膨胀位移与温度的关系,进而得出平均线膨胀系数.结果表明:在同一温度条件下,随颗粒理论体积分数增加,复合材料的平均线膨胀系数减小.温度是影响平均线膨胀系数的重要因素.当试样温度在50～300℃时,随温度增加,平均线膨胀系数逐渐增加;当试样温度在300～500℃时,随温度增加,平均线膨胀系数逐渐减小;300℃时平均线膨胀系数最大.用Rom、Turner和Kerner模型计算了理论热膨胀系数.比较发现,实测值更接近Turner模型理论预测值.最后通过界面残余热应力分析指出具有高温低膨胀性的(Al2O3+Al3Zr)p/Al-12%Si颗粒增强铝基复合材料能有效防止材料高温时的塑性变形.

Al-12 % Si and Zr（ CO3 ）2 were selected as reactive components to synthesize Al2O3, Al3Zr particulate reinforced Al- 12 % Si matrix composites. The as-cast samples were got via a rapid solidifying method. The relationship between thermal expansion displacement and temperature in the range of 50 to 500 ℃ was tested using a thermal expansion instrument and the average linear coefficient of thermal expansion （ALCTE） was also calculated. The results show that the ALCTE decreases with the increase in theoretical volume fraction of particulates （TVFP） at the same temperature. Meanwhile temperature is an important factor to influence the ALCTE. At 50 to 300℃ the ALCTE increases gradually with the increase in temperature, while at 300 to 500 ℃ it decreases gradually with the increase in temperature, and the value arrives maximum at 300 ℃. Furthermore the theoretical ALCTE values were calculated with the Rom, Turner and Kerner models individually. The test results of ALCTE are similar to the values from the Turner model. At last it is concluded by analyzing the residual thermal stress at interfaces that the （Al2O3 ＋ Al3Zr）p/Al-12 % Si composite can prevent the materials from plastic deforming at high temperature because of its low thermal expansion.