STUDY ON MECHANICAL AND WEAR CHARACTERISTICS OF IN-SITU ZrB2/ALUMINUM ALLOY COMPOSITES PROCESSED BY SALT-MELT REACTION

In the present work, ZrB2/Al alloy composites were processed through the salt-melt reaction technique. Aluminum alloy (LM4) was taken as a matrix material. The ZrB2 reinforcement particles were formed in-situ by the reaction of precursor salts K2ZrF6 and KBF4 within the aluminum melt. Relative to the parent alloy, the hardness of the composites reinforced with 2.5, 5 and 7.5 wt.% ZrB2 showed an increase of 8.24%, 17.64% and 33.77%, respectively. The tensile strength also improved initially but decreased when the amount of reinforcement exceeded 5-wt.%. The elongation varied in the same fashion as the tensile strength. The microstructure of the composites showed moderately uniform distribution of particles. However, agglomeration of reinforcement particles became a problem at the highest amount of reinforcement. Wear experiments to determine the influence of load, sliding velocity, sliding distance and the amount of reinforcement on the wear rate of composites were designed in accordance with the Taguchi model. The results revealed that both load and sliding velocity have the highest influence.