Microstructure, Tensile Properties, and Wear Resistance of in Situ TiB2/6061 Composites Prepared by High Energy Ball Milling and Stir Casting

In-situ synthesized TiB 2 /6061 composites were prepared from Al-K 2 TiF 6 -KBF 4 by high energy ball milling and stir casting. Phase analysis and microstructure observation of the samples were characterized by XRD, SEM and EDS, respectively. The effect of TiB 2 particle content on the microstructure, tensile properties and wear resistance of the composites was studied. The results show that the average size of TiB 2 particles is 1 μm, which is polygonal shape. The average grain size of the composites can be refined significantly as the TiB 2 particle mass content increased from 1 to 3%; however, the grain coarsening occurs in the 5 wt.% TiB 2 /6061composites. The 3 wt.% TiB 2 /6061 composites have best tensile strength, yield strength and Young’s modulus among the composites in ranges of the TiB 2 mass fraction from 1 to 5%. Strengthening mechanisms of the TiB 2 /6061 composites were fine grain strengthening, Orwan strengthening and CTE strengthening, in which the CTE strengthening plays an important role as increasing the TiB 2 content. The pin-on-disk wear test results indicated that the average friction coefficient and wear rate of the TiB 2 /6061 composites increased firstly and then decreased with increasing the TiB 2 content from 1 to 5 wt.%. The wear mechanism of the TiB 2 /6061 composites was discussed.