Production of high-density Fe–16 at.% Al alloy and Fe–16 at.% Al–15 vol% Al2O3 composite by mechanical smearing and hot isostatic pressing

Fe–16 at.% Al alloy matrix and Fe–16 at.% Al–15 vol% Al₂O₃ composite have been made from iron, aluminium and alumina powder by mechanical smearing at room temperature followed by hot isostatic pressing (HIP) at 1200°C. The HIP compacts possess 97 and 99% theoretical densities respectively, resulting in very good hardness values. Ultra-micro-indentation techniques revealed that the composite has three distinct zones so far as hardness is concerned. These are Al₂O₃-rich grain boundaries, an interface region of functionally graded material, and a matrix of Fe–16 at.% Al. The incorporation of the Al₂O₃ phase significantly improves the hardness. From indentation fracture toughness tests, both materials showed an estimated minimum fracture toughness of 15 MPam^1/2, which is good for these types of materials.