Experimentation on Mechanical properties of Al 7075 reinforced with Hafnium carbide, Silicon nitride, and Molybdenum Disulfide hybrid composites

Abstract

The objective of the present research is to investigate the Mechanical properties of Hafnium carbide (HfC), Silicon Nitride (Si₃N₄) and Molybdenum Disulfide (MoS₂) reinforced with Al 7075. The secondary particles like Si₃N₄ (2 to 8) wt.% increase in the step of 3%, HfC (0.5 to 2) wt.% increase in the step of 0.75% and MoS₂ (2 to 5) wt.% increase in the step of 1.5 % are reinforced in base material Al7075 alloy using stir casting methodology. The casted specimen is machined using wire cut EDM as per the ASTM standards. Vickers’s microhardness test and Ultimate tensile strength were performed; the result indicates Al7075 with 5wt.% Si₃N₄, 1.25wt.% HfC, 3.5wt.% MoS₂ increases the hardness and tensile strength by indicating excellent mechanical properties, however, adding more reinforcements decreases hardness and tensile strength. The fatigue tests were performed on different specimens based upon the tension-compression cyclic loading, calculated the endurance limit, stress and no failure mode of each specimen by predicting the cut off value at 10⁴ cycles; the Al7075 with 5wt.% Si₃N₄, 1.25wt.% HfC, 3.5wt.% MoS₂ shows maximum stress at 1.6×10⁴ Cycles. The SEM analysis after casting shows the disperse of reinforcements with the base alloy, and the fractography analysis of tensile test shows the fracture behaviour of the specimens that show the changes of behaviour from ductile to brittle by adding more reinforcements. The EDS shows the presence of materials based upon the wt.% added.