Mg2 B2 O5 whisker-reinforced aluminum composite was fabricated by squeeze casting method, and the composite was annealed at 450 ℃ for different time. The effects of annealing time on the ultimate tensile strength at room temperature, thermal expansion behaviors, and the matrix texture were studied. The results show that the annealing can effectively improve the ultimate tensile strength of the composite. The ultimate tensile strength increases with the annealing time increasing, and attains its highest strength (295 MPa) at the annealing time of 5 h, but the strength decreases slightly to 285 MPa at the annealing time of 7 h. It is also found that the coefficient of thermal expansion increases with the annealing time increasing first and then decreases, but the coefficients of the composite after annealing are larger than that of untreated composite.%采用挤压铸造方法制备了硼酸镁晶须增强纯铝基复合材料，在450℃下对其进行了不同时间的退火处理，研究了不同退火时间对复合材料的室温力学性能、热膨胀行为及基体织构的影响．试验结果表明，退火处理能有效提高复合材料的抗拉强度，随着退火时间的增加材料的拉伸强度也逐渐增加，在5 h时达到最大值295 MPa，7 h时略有下降，为285 MPa．复合材料的热膨胀曲线表明，退火处理会使材料的热膨胀系数变大，随着退火时间的增加，材料的热膨胀系数先增加后减小，但始终高于未退火处理的材料．
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