Creep rupture life prediction of short fiber-reinforced metal matrix composites

Abstract

The creep rupture life of an Al/Al₂O₃ composite and its creep behavior were studied. The metal matrix composite was produced by using a squeeze casting technique. High-temperature tensile tests and creep experiments were conducted on a 15 vol pct alumina fiber-reinforced AC2B Al alloy metal matrix composite (MMC). The high-temperature tensile strength of Al/Al₂O₃ composite is 14 pct higher than that of an AC2B Al alloy. The steady-state creep rate and the creep life were measured. The stress exponent in Norton’s equation and the activation energy were computed. The stress exponents of the AC2B and Al/Al₂O₃ composites were found to be 4 and 12.3, respectively. The activation energy of the AC2B and Al/Al₂O₃ composites was found to be 242.74 and 465.35 kJ/mol, respectively. A new equation for predicting creep life was established, which was based on the conservation of the creep strain energy. The theoretical predictions were compared with those of the experiment results, and a good agreement was obtained. It was found that the creep life is inversely proportional to the (n + 1)th power of the applied stress and strain failure energy of creep is conserved. The creep fracture surface, examined by scanning electron microscopy (SEM), showed that the MMC specimen failed in a brittle manner.