TRIBOLOGICAL PROPERTIES OF ALUMINUM-ALLOY MATRIX TIB2 COMPOSITE PREPARED BY IN-SITU PROCESSING

An investigation of the wear behavior, in lubricated sliding and rolli ng of in situ prepared TiB2 particle-reinforced 2024 T4 Al alloy matri x composites against 52100 steel and hardened pearlitic nodular cast i ron, respectively, was undertaken. In sliding contact, the 10 vol pet 0.3-mu m TiB2-metal matrix composite (MMC) showed slightly less wear t han the 10 vol pet 1.3-mu m TiB2-MMC. Transmission electron microscopy of cross sections, taken normal to the wear track and parallel to the sliding direction, revealed that the TiB2 particles on the wear track were polished and particle pullout was largely absent. This was attri buted to the strong interfacial bonding between the Al-alloy matrix an d the TiB2 reinforcing phase. The TiB2 particles on the wear track inh ibited spalling; Subsurface damage of the MMC did not occur. The wear of the steel mating surfaces worn against the TiB2-MMCs was minor and caused by the cutting action of the TiB2 particles that resided on the MMC wear track. In rolling contact, the 0.3-mu m-size TiB2-MMC showed 5 times higher weight loss than the 1.3-mu m TiB2-MMC for the same co ntent of reinforcement, but the weight loss of the cast iron mating su rface was less for the former. For the smaller particle size, the wear of 5 and 10 vol pet TiB2-MMCs was the same. A high density of surface cracks was present on the wear track of the 0.3-mu m TiB2-MMC but not on the 1.3-mu m MMC. The significance of strong particle/matrix inter facial bonding and particle size effect on the wear behavior of cerami c particulate-reinforced MMCs in lubricated sliding and rolling wear i s discussed.