基体合金相组成对硼化物增强镁锂基复合材料组织和性能的影响

采用原位合成法制备了硼化物增强Mg-Li基复合材料。针对基体为Mg-14Li-1Al-1Y的复合材料力学性能仍不能满足工业应用需求的缺陷,以Mg-9Li-1Al-1Y镁锂合金为基体制备了硼化物增强镁锂基复合材料(其成分为(Mg-9Li-1Al-1Y)-6B_4C)。研究了Li含量对基体合金和复合材料组织和性能的影响。试验结果表明:合金Mg-9Li-1Al-1Y与合金Mg-14Li-1Al-1Y相比,其双相区组织晶粒更加细小,各力学性能均有所提高。(Mg-9Li-1Al-1Y)-6B_4C复合材料与Mg-9Li-1Al-1Y合金相比,硬度提高了66%,抗拉强度提高了31.33%,伸长率降低了15.5%。(Mg-9Li-1Al-1Y)-6B_4C与(Mg-14Li-1Al-1Y)-6B_4C相比,屈服强度降低了15.4%,硬度提高了29.3%,抗拉强度和伸长率基本保持不变。以上试验结果表明:随着Li含量的降低复合材料的力学性能没有得到提高,没有实现基体合金强度增加从而相应复合材料强度增加的试验预期,说明相比镁锂基复合材料强化机制中第二相强化与细晶强化的作用,基体强化作用较弱难以体现。

Effect of Phase Composition of Matrix Alloys on Mg-Li Based Composites Reinforced With Boride

In this paper,we have prepared Mg-Li based composites reinforced with boride by in situ synthesis.For mechanic properties of Mg-14Li-1Al-1Y based composites cannot meet the requirement of industrial applications,the research has prepared composites reinforced with boride based on Mg-9Li-1Al-1Y (its composition is (Mg-9Li-1Al-1Y)-6B4C).The effect of Li content on microstructure and properties of the matrix alloys and composites were studied.The results show that compared with Mg-14Li-1Al-1 Y,the dual phase microstructure of Mg-9Li-1Al-1Y is finer and the mechanical properties are improved.Compared with Mg-9Li-1Al-1Y,the hardness and the tensile strength of (Mg-9Li-1Al-1Y)-6B4C are enhanced by 66％ and 31.33％,respectively,while the elongation decreases by 15.5 ％.Compared with (Mg-14Li-1Al-1Y)-6B4C,the yield strength of (Mg-9Li-1Al-1Y)-6B4C decreass by 15.4％,the hardness increases by 29.3％,and the tensile strength and elongation remains unchanged.The above experimental results show that the mechanical properties of composites have not been improved with the deduce of Li content.It does not reach the expectation that composite strength can be improved with strength increase of corresponding alloys.The matrix strengthening is too weak to reflect in comparison to the second phase strengthening and fine-grain strengthening of Mg-Li based composite reinforcement mechanism.