Fabrication and Corrosion Behaviour of Aluminium Hybrid and Non-hybrid MMCs Reinforced with B4C and Gr Additions by Powder Metallurgy Technique

Abstract

In this tentative study, aluminium metal matrix composites (AMMCs) and aluminium metal matrix hybrid composites (AMMHCs) were fabricated by using powder metallurgy method. In this work, boron carbide (B4C) and graphite (Gr) are the two types of reinforcements used in the fabrication of the composites, and these are added to the base aluminium alloy Al2024 used as matrix. The used reinforcements, in which one is a ceramic harder material boron carbide (B4C) added in AMMCs and the other element is a softer material Graphite (Gr) is added in AMMHCs along with same B4C. In the initial stage, various weight-based aluminium metal matrix composites (AMMCs) are fabricated by choosing Al 2024 as the matrix and are reinforced with the hard ceramic material which is boron carbide (3, 6, 9, 12 and 15%). In the lateral stage, aluminium metal matrix hybrid composites (AMMHCs) are also being fabricated by using same aluminium used as matrix and are reinforced with fixed percentage of soft solid lubricant Gr (3%) along with varying percentages of B4C (3, 6, 9, 12 and 15%). All these composites are fabricated by using powder metallurgy technique; FESEM and microstructural analysis shows the presence and uniform distribution of reinforced particles in aluminium alloy. Corrosion test was carried out as per ASTM 59 standards for a definite time interval on all the fabricated specimens by using potential dynamic polarization technique in aerated 3.5% NaCl solutions with PH adjusted to 10 by adding potassium hydroxide. After the test, corrosion behaviour of all the samples is analysed by Tafel extrapolation technique. The surface morphology of the specimen before and after corrosion was studied using the FESEM and microstructure images.