Mg对原位自生TiB_(2)/Al-4.5Cu复合材料微观组织及力学性能的影响  

Effect of Mg on microstructure and mechanical properties of in-situ TiB_(2)/Al-4.5Cu composites

作　　者：薛彦庆 郝启堂[1] 李新雷[1] 魏典 李博[1] 余量量 Yanqing XUE;Qitang HAO;Xinlei LI;Dian WEI;Bo LI;Liangliang YU(School of Materials Science and Engineering,Northwestern Polytechnical University,Xi’an 710012,China)

机构地区：[1]西北工业大学材料学院,西安710012

出　　处：《复合材料学报》2021年第5期1507-1516,共10页Acta Materiae Compositae Sinica

基　　金：国家自然科学基金(51375391);陕西省重点研发计划(2020GY-117);西北工业大学凝固技术国家重点实验室自主研究课题资助项目(2019-TZ-03)。

摘　　要：采用Al-K2TiF6-KBF4混合盐原位自生反应法,制备了不同Mg质量分数的3wt%TiB2/Al-4.5Cu复合材料。采用SEM、TEM、HM硬度测试和室温拉伸等方法研究了Mg含量和多级热处理对3wt%TiB2/Al-4.5Cu复合材料微观组织和力学性能的影响。微观组织观察发现:Mg质量分数为3wt%时,经过多级热处理后,TiB2颗粒的团聚现象明显改善,反应生成的TiB2颗粒平均尺寸约为130 nm,基体内伴随有大量弥散分布的纳米级颗粒,且α-Al的晶粒尺寸也明显减小。力学测试结果表明:多级热处理后,3wt%TiB2/Al-4.5Cu复合材料的硬度和抗拉强度随Mg含量的增加而提高,但过量的Mg (≥4wt%)会造成TiB2颗粒细化效果下降。分析表明:Mg的加入能够降低TiB2/α-Al界面能,减少脆性相Al3Ti、 Al2B的生成,并通过反应生成的MgAl2O4使界面结构变成TiB2/MgAl2O4/α-Al,从而有效抑制了TiB2的团聚,改善了TiB2颗粒与Al液界面的润湿性,提高了形核率,进一步细化了α-Al晶粒尺寸。The 3 wt% TiB2/Al-4.5 Cu composites with different mass fraction of Mg were fabricated by Al-K2TiF6-KBF4 molten salt reaction method. The influences of Mg and multistage heat treatment on the microstructure and mechanical properties of the 3 wt% TiB2/Al-4.5 Cu composite were studied by means of SEM, TEM, HM hardness test and room temperature tensile test. The microstructure observation shows that the agglomeration of TiB2 particles is obviously improved after multistage heat treatment along with addition of Mg, In particular, with 3 wt% Mg, the average size of TiB2 particles is about 130 nm, accompanied by a large number of dispersed nano particles, and the grain size of α-Al is also significantly reduced. The mechanical test results show that after multistage heat treatment,the hardness and tensile strength of the 3 wt% TiB2/Al-4.5 Cu composite are enhanced with the increase of Mg content. However, excess Mg content(mass fraction≥4 wt%) will decrease the refinement effect of TiB2 particles. The analysis reveals that addition of Mg can reduce the interfacial energy of TiB2/α-Al and block the formation of brittle phase Al3Ti, Al2B. Meanwhile, the MgAl2O4 formed by reaction makes the interface become into the TiB2/MgAl2O4/α-Al, which could restrain the agglomeration of TiB2 particles and improve the wettability of the interface between TiB2 particles and Al liquid, increase the nucleation rate and refine the grain size.

关 键 词：TiB_(2)/Al-4.5Cu复合材料 Mg 微观组织 硬度 力学性能 

分 类 号：TB333[一般工业技术—材料科学与工程] TG290.2[金属学及工艺—铸造]