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用石墨埋烧方法制备Fe/Al_2O_3复合材料,对其力学性能和微观结构进行了分析。结果表明:Fe/Al_2O_3复合材料的弯曲强度与断裂韧性均随Al_2O_3含量的升高先升高后降低,当Al_2O_3含量(质量分数)为70%时,其弯曲强度与断裂韧性分别达到602.49 MPa和9.33 MPa·m~1/2,其硬度随Al_2O_3含量先降低后升高。在烧结过程中在Fe颗粒周围形成一种成分为FeO与FeAl_2O_4的壳体,在壳体与Fe颗粒之间存在微裂纹缺陷。壳体的形成和壳体与金属颗粒间的微裂纹钝化了外部应力,从而提高了复合材料的韧性。
Preparation of Fe / Al_2O_3 composites by graphite burying method and their mechanical properties and microstructure were analyzed. The results show that the flexural strength and fracture toughness of Fe / Al_2O_3 composites firstly increase and then decrease with the increase of Al_2O_3 content. The bending strength and fracture toughness of Al_2O_3 composites reach 602.49 MPa and 9.33 MPa respectively · M ~ 1/2, the hardness decreases with Al 2 O 3 content first and then increases. During sintering, a shell of FeO and FeAl_2O_4 is formed around the Fe grains, and there are micro-crack defects between the shell and the Fe grains. The formation of the shell and the micro-cracks between the shell and the metal particles passivate external stresses, thereby increasing the toughness of the composite.