Abstract:
Aluminum based metal matrix composites (MMC) containing 10 wt. %, 20 wt. % and 30 wt. % beryl were fabricated using powder metallurgy route. The beryl as a mineral phase was initially crushed, and mechanically sieved to various sizes. The final particle sizes in the range of 50±10 µm were made. Commercially available Al powder with an average particle size of 40±5 µm, and beryl content in Al was varied from 10, 20, and 30 wt. %. The green pellets were made to 25 mm diameter with a load of 1.02 MPa, were sintered in a vacuum furnace maintained at 500◦,550◦ and 600ºC.The sintered samples with varying quantities of beryl, were subjected to hardness measurement and microstructural details. The hardness results clearly demonstrated that increasing the sintering temperature in powder metallurgy route was responsible for better interfacial bonding and reduced porosity, increased hardness values. Al-10, 20 and 30-wt% beryl MMC exhibited hardness of 55 VHN, 58 VHN, and 72 VHN, respectively. The microstructural examination clearly demonstrated that vacuum sintered at 600ºC has led to improved density level. The interfacial bonding between the Al matrix and beryl particles observed was excellent. Sintering temperature of 600◦C, showed superior hardness and strength values as compared to Al-beryl MMC processed through liquid metallurgy vortex route technique.
Keywords: Sintering, Beryl, Metal matrix Composite, hardness, Powder Metallurgy