Fracture toughness of the eutectic alloy Al3Nb-Nb2Al

Presenting high fracture toughness is a decisive condition to any structural material, and when considering brittle alloys, the Vickers indentation method to determine fracture toughness is an interesting alternative. Like many other intermetallics, the Al3Nb-Nb2Al eutectic alloy shows high strength at high temperatures and low fracture toughness at room temperature. Al3Nb-Nb2Al samples, both in the as-solidified condition and in the directionally solidified condition, had their hardness and fracture toughness determined by the Vickers indentation method. Lower values of hardness were found when higher loads were used, and fracture toughness was found to be about 2.0 MPa m(1/2). The as-solidified condition is harder and less tough, and when fracture occurs, cracks always develop by cleavage. (C) 2003 Elsevier Science B.V. All rights reserved.