Microstructure And Properties Of In-situ Synthesis TiC Dispersion Reinforced 6A02 Al Matrix Material

Particulate dispersion reinforced Al matrix materials have received growing attention of materials scientists in recent decades, which posses a wide variety of superior properties over traditional metal materials, e.g. high specific strength, good thermal stability, good wear resistance and excellent properties at elevated temperatures. Moreover, their costs are lower than other methods. Applications of in-situ synthesis alloys as structure materials have been increased in many industries, such as defense, aerospace and automotive industries. In this paper, in-situ synthesis was used to fabricate the TiC particulate reinforced aluminum alloy 6A02(LD2) matrix material. The microstructure, mechanical properties as well as wear resistance have been extensively investigated using optical microscope(OM), scanning electron microscope(SEM), X-ray diffractometer(XRD), inductively coupled plasma(ICP) and other modern equipments. Especially, the ways to decrease the size of TiC particles and improve TiC dispersion have been investigated.The effect of additions of TiC particles on the microstructure and mechanical properties of TiC/6A02 matrix materials have been studied. The results showed that the formation of TiC particles in the matrix resulted in the refinement of as-cast microstructure, and improved the strength of the materials significantly at ambient and elevated temperatures, and the strength of the materials increased with the increased percentage of TiC, though the additions of TiC reduced the ductility of the materials.The main work of the present study is on the way to decrease the size of TiC particles. The size of TiC particles have been reduced with increased Al content in Al-Ti-C powder blocks, but excessive Al content result in inadequacy in reaction, and the Al3Ti phase as the middle production remained in the alloys, therefore, it weakened the strengthening effect of TiC particles; The size of TiC particles refined with addition of CeO2 which instead of rare earth Ce. However, the mechanical properties of alloys deteriorated by the massive phase Al11Ce3; The wettability between matrix and TiC has been improved with addition of Mo during the reaction, and results in the refining of the size of TiC particles as well as distributing TiC dispersion.Scanning electron microscopy(SEM) showed that the fracture modes of the TiC/6A02 materials prepared in the present work are all ductile dimples. The fracture is equiaxed fine dimples when TiC particles are fine and uniform; Due to the aggregation of TiC particles, the number of dimples was decreased and the dimension was increased.The study on the lubricated sliding wear behavior of TiC/6A02 alloys revealed that the wear resistance is notable superior to that of 6A02 matrix alloy, and is greatly enhanced with the increase of particles volume fraction. The more fine and uniform of TiC particles, the more contribution to wear resistance would gain. The SEM observation of wear surface and subsurface showed that the wear mechanism of both 6A02 matrix alloy and Al matrix material includes adhesive wear and grinding-particle abrasive wear.