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在常压下通过熔渗工艺将AlSi7Mg合金渗入由AlN粉末模压成形、预烧所获得的预烧结坯中,得到了不同Al含量的Al/AlN复合材料。采用X射线衍射仪对复合材料的相组成进行了测试,采用金相显微镜和SEM对其显微组织进行了观测,并对不同Al含量的Al/AlN复合材料的维氏硬度、抗弯强度、热膨胀系数及导热系数等进行了测试分析。结果表明:在900℃下,N2气氛中通过熔渗工艺可以制备出相对密度高于98.5%的Al/AlN复合材料,且在整个制备过程中AlN坯体尺寸几乎没有变化;Al/AlN复合材料的硬度和强度随Al含量的增加而降低,导热系数和热膨胀系数则随Al含量增加有所增加;Al体积分数为38%和62%时,Al/AlN复合材料维氏硬度分别为HV 715和HV 203,抗弯强度分别为492MPa和388MPa,室温导热系数分别为73W/(m.K)和120W/(m.K),室温至200℃的平均线膨胀系数分别为8.60×10-6 K-1和1.11×10-5 K-1;Al/AlN复合材料的热膨胀系数与Al含量的关系符合Kerner模型。
The AlSi7Mg alloy infiltrated into the pre-sintered billet obtained by press-molding AlN powder by infiltration process under ordinary pressure to obtain Al / AlN composite materials with different Al contents. The phase composition of the composites was tested by X-ray diffractometer. The microstructure of the composites was observed by optical microscope and SEM. The Vickers hardness, flexural strength, Thermal expansion coefficient and thermal conductivity were tested and analyzed. The results show that Al / AlN composites with relative density higher than 98.5% can be prepared by melt infiltration at 900 ℃ in N2 atmosphere with almost no change in the AlN content during the whole preparation process. Al / AlN composites Hardness and strength decrease with the increase of Al content, while the thermal conductivity and thermal expansion coefficient increase with the increase of Al content. Vickers hardness of Al / AlN composites are HV 715 and HV respectively when the volume fraction of Al is 38% and 62% HV 203, flexural strength of 492MPa and 388MPa, room temperature thermal conductivity of 73W / (mK) and 120W / (mK), the average linear expansion coefficient of room temperature to 200 ℃ were 8.60 × 10-6 K-1 and 1.11 × 10-5 K-1. The relationship between the thermal expansion coefficient and Al content of Al / AlN composites accords with Kerner model.