高压扭转对SiC_P/Al复合材料微观组织和力学性能的影响

为研究大塑性变形对金属基复合材料微观组织和力学性能的影响,利用高压扭转工艺(HPT)在200℃下将纯Al粉末和经氧化处理的SiC粉末混合固结成10wt%SiC_P/Al复合材料。采用TEM观察HPT变形后不同圈数试样的SiC-Al界面及Al基体微观组织,采用EDS能谱仪分析界面处原子扩散现象,采用万能拉伸试验机测试研究不同扭转圈数试样的力学性能。结果表明:不同圈数试样Al基体内出现大量位错、非平衡晶界等晶格缺陷;组织内存在两种SiC-Al界面,含SiO_2层的原始界面和因颗粒破碎而新生成的界面。两种界面结合良好,界面处元素相互扩散;随着扭转圈数的增加,10wt%SiC_P/Al复合材料抗拉强度增加,延伸率得到较大提高。分析发现高压扭转后不同圈数组织内产生的大量晶格缺陷和细小晶粒,促进界面处元素的相互扩散,使界面结合良好,同时大量晶格缺陷和细小晶粒的产生以及结合良好的SiC-Al界面是SiC_P/Al复合材料力学性能大幅提升的主要原因。

Influence of high pressure torsion on microstructure and mechanical properties of SiCP/Al composites

In order to research the influence of severe plastic deformation on microstructure and mechanical properties of metal matrix composites,powder mixture of pure Al and oxidized SiC were consolidated into 10 wt% (mass fraction) SiCP/Al composites at 200℃ by high-pressure torsion(HPT).The Al microstructure and SiC-Al interface of different torsion numbers were studied by TEM.The energy dispersive spectrometer(EDS) was used to analysis the elements diffusion.The mechanical properties of different torsion numbers were studied by universal testing machine.The results show that there are a large number of lattice defect in Al matrix after deformation of different torsion numbers,such as dislocation and non-equilibrium grain boundary.There are two different SiC-Al interface which is the SiC-Al interface with SiO2 layer and new interface that formes between Al matrix and broken SiC particles.SiC-Al bonding is good and elements mutually diffuse at the interface.The tensile strength of 10 wt% SiCP/Al is increased significantly and the elongation is greatly improved with the increase of torsion numbers.The analysis shows that a large number of lattice defects and fine grains are produced in the samples after deformation of different torsion numbers.The lattice defects and fine grains enhance the elements diffusion and make the interface bonding better.Lattice defects and better interface are the main reasons that the mechanical properties of 10 wt% SiCP/Al are greatly improved.