Microhardness and Microstructural Behavior of AA7068/SiC Metal Matrix Composites Synthesized by Powder Metallurgy

Abstract

If anybody is missing any arm or leg, a prosthetic limb can be replaced to take care of their activities by themselves. Manufacturing of prosthetic limbs for such persons should be lightweight and requires improved hardness. Hence, silicon carbide (SiC) was incorporated into aluminum alloy (AA7068) to produce composites by powder metallurgy technique with different weight percentages of SiC (3, 6 and 9%) along with base alloy. A compaction pressure of 318 MPa was applied and sintered at a temperature of 560°C for an hour. Vickers microhardness test was carried out to find out the microhardness values. Wear experiments were conducted with a velocity of 1.2 m/s over a sliding distance of 2.5 km of load 5 N. Field emission scanning electron microscopy (FESEM) analysis was carried out to investigate the worn surface. Experimental results showed that the Vickers microhardness number has been increased to a maximum of 55 VHN by the addition of 9% SiC particles which were 66.7% more than the base alloy. Wear experiments exposed an improved wear resistance by the addition of SiC particles. AA7068-9% SiC composite exhibited maximum wear resistance. FESEM analysis revealed that abrasion and oxidation were the predominant wear modes for the produced AA7068/SiC composites. The prosthetic limb produced using such composite combination would be lightweight with the improved hardness which would serve the persons better to perform their daily activities.