【摘要】 采用机械合金化-放电等离子体烧结(MA-SPS)技术原位合成近全致密的Al13Fe4/Al复合材料.在MA过程中采用磨球级配对材料的组织结构和性能进行了优化.利用XRD,SEM,TEM,显微硬度计和力学性能测试系统等手段对粉末及烧结试样的组织结构和性能进行了分析表征.结果表明,相同MA时间下,采用磨球级配可有效提高球磨效果,其粉末粒径分布更均匀,固溶度也得到很大的提高.SPS烧结后,复合材料的组织由a-Al和金属间化合物Al13Fe42相构成.金属间化合物Al13Fe4相的形态分为大颗粒(1~2 mm)、超细颗粒(0.1~1.0 mm)和纳米颗粒(20 nm)3种,其中大颗粒和超细颗粒Al13Fe4由未固溶的Fe与Al直接反应原位生成,纳米颗粒Al13Fe4是Fe从过饱和Al(Fe)固溶体中析出生成.采用磨球级配处理的Al-10Fe合金含有更多大颗粒a-Al和超细颗粒Al13Fe4,因此它具有更优的综合力学性能,显微硬度为227 HV,抗压强度为845.8 MPa,最大塑性变形量为13.6%.更多还原

【Abstract】 Al-Fe alloys are widely applied in automobile, aerospace, military industry and other fields owing to their high specific strength, high specific stiffness and good stability of the microstructure originating from the low diffusivity of Fe in Al. However, conventional casting method leads to inferior mechanical properties of Al-Fe alloys due to the coarse grain microstructure, which cannot meet application requirements. In this work, fully densed Al13Fe4/Al composites were fabricated by combination of mechanical alloying and spark plasma sintering(MA-SPS) approaches. Effect of gradation of grinding balls on microstructure and properties of composites was investigated by means of XRD, SEM, TEM, hardness and compressive test. The results showed that the size of powders became more uniform by ball gradation in MA treatment, and solid solubility was greatly enhanded as well.Furthermore, the Al-Fe powder after MA using a single grinding ball size showed the microstructure of tiny white Fe particles on the surface of each particle, while no white Fe particles were observed for the one with ball gradation, which confirmed that ball gradation was more beneficial to the mixture and solid solution of Al and Fe, resulting in more homogeneously distributed powders with smaller particle sizes of 10 μm. The composites after SPScontained a-Al phase and intermetallic compound Al13Fe4. Three types of Al13Fe4 were observed: large particles(1~2 μm), ultrafine particles(0.1~1.0 μm) and nano-particles(about 20 nm). The large particles and ultrafine Al13Fe4 formed by the reaction between undissolved Fe particles and the Al melt while nano-particles of Al13Fe4 originated from the precipitation of supersaturated Al(Fe) solid solutions. The sintered sample with ball gradation after SPS showed optimized microstructure with coarser a-Al particles and ultrafine Al13Fe4 particles, resulting in good comprehensive properties with 227 HV in microhardness, 845.8 MPa in compressive strength and 13.6% in plastic deformation. The combination of large quantities of coarse a-Al particles and ultrafine Al13Fe4 particles were considered as the reason for high strength and high toughness of Al-Fe alloy.更多还原