材料期刊网

An investigation has been carried out to study the low-cycle fatigue lives and cyclic stress response characteristics of a particulate SiC-reinforced 2024Al and its unreinforced matrix alloy at 22 and 190 degrees C. The specimens were cyclically deformed with fully-reversed loading under plastic-strain amplitudes. The test results showed that the cyclic stress response characteristics of the composite and the 2024Al alloy were similar to each other in spite of changing the test temperature. The composite and its unreinforced counterpart generally exhibited cyclic hardening at 22 degrees C and cyclic softening at 190 degrees C. Increase in low-cycle fatigue resistance for both the composite and the aluminium alloy was observed as the test temperature rose from 22 to 190 degrees C. For a given temperature the low-cycle fatigue endurance of the composite was lower than that of the unreinforced matrix alloy in the high and middle strain regions, however, at low strains the difference in fatigue endurance between the composite and the aluminum alloy decreased. The mechanism of strain in the composite, i.e. the strain in the composite was nearly completely sustained in the soft matrix, and the strain concentration adjacent to the reinforcement were two important factors that led to the shorter strain-fatigue life for the composite. (C) 1999 Elsevier Science Ltd. All rights reserved.