(Ti2Al20La+Al3Ti)/Al-7Si复合材料的显微组织、力学性能和耐磨性能

Microstructure, Mechanical Properties and Wear Resistance of (Ti2Al20La+Al3Ti)/Al-7Si Composites

摘要:

采用熔配法制备了富含Ti₂Al₂₀La和Al₃Ti增强相的(Ti₂Al₂₀La+Al₃Ti)/Al-7Si复合材料，研究了不同Al-Ti-La合金添加量对复合材料的显微组织、力学性能及耐磨性能的影响。结果表明：向Al-7Si合金中加入10wt% Al-Ti-La合金得到的(Ti₂Al₂₀La+Al₃Ti)/Al-7Si复合材料由细小的α-Al晶粒、短棒状共晶Si、块状Al₃Ti及Ti₂Al₂₀La相所组成。复合材料的抗拉伸强度、延伸率、硬度分别为176.9 MPa、11.62%、73.2 HV，与Al-7Si合金相比，分别提高了13.4%、57.0%、26.2%，具有较高的强塑性，此外复合材料的耐磨性能也提高了20.1%。复合材料性能的提升有两方面影响因素。一方面是由于强化相Al₃Ti与铝基体交界处形成了Al₃Ti过渡层，且该过渡层与Al₃Ti呈半共格关系。另一方面，强化相Ti₂Al₂₀La中的La元素能够吸附Si元素，导致Si元素富集在Ti₂Al₂₀La相边缘，形成半共格的Si层。

Abstract:

(Ti₂Al₂₀La+Al₃Ti)/Al-7Si composites rich in Ti₂Al₂₀La and Al₃Ti reinforcement phases were prepared by the melt blending method. The influence of the addition amount of Al-Ti-La alloy on the microstructure, mechanical properties, and wear resistance of the composites was analyzed. Results reveal that the (Ti₂Al₂₀La+Al₃Ti)/Al-7Si composite (adding 10wt% Al-Ti-La alloy into the Al-7Si alloy) is composed of fine α-Al grains, short rod-like eutectic Si, and blocky Al₃Ti and Ti₂Al₂₀La phases. The tensile strength, elongation, and hardness of the composite are 176.9 MPa, 11.62%, and 73.2 HV, increased by 13.4%, 57.0%, and 26.2% compared with those of the Al-7Si alloy, respectively. It is suggested that the (Ti₂Al₂₀La+Al₃Ti)/Al-7Si composite exhibits relatively high plasticity. Furthermore, the wear resistance of the composites is increased by 20.1%. The performance enhancement is attributed to two key mechanisms. One is the formation of Al₃Ti transition layer at the interface between the Al₃Ti reinforcement phase and the aluminum matrix, which establishes a semi-coherent relationship with Al₃Ti phase. The other is the adsorption of element Si by element La within the Ti₂Al₂₀La reinforcement phase, leading to Si enrichment at the edges of the Ti₂Al₂₀La phase and thereby forming a semi-coherent Si layer.