FRACTURE TOUGHNESS MEASUREMENTS AND FAILURE MECHANISMS OF METAL MATRIX COMPOSITES

Abstract— This paper compares the fracture toughness values obtained from two different specimen geometries, i.e. pre‐cracked compact tension and chevron‐notched short rod. The former is in widespread use, however, the latter has significant advantages in that no pre‐cracking is required resulting in more economical use of material and reduced machining. Four 6061‐aluminium‐matrix composites reinforced with discontinuous alumina particles were investigated. Good agreement in fracture toughness values from the two specimen geometries was obtained for all the materials and all the heat treatments examined. Detailed analyses of the fracture surfaces were used to identify the fracture mechanisms. The effects of specimen geometry, volume fraction of reinforcement and ageing treatment on fracture toughness are discussed.