The high-temperature creep behaviour of 2124 aluminium alloys with and without particulate and SiC-whisker reinforcement

Tensile creep behaviour of SiC-whisker and particle reinforced 2124Al-matri x composites and unreinforced 2124Al alloy was investigated at 573-673 K. T he results showed that the unreinforced 2124Al alloy exhibited apparent str ess exponents of 4.7-8.5 and an apparent activation of 288 kJ/mol, while th e particulate and whisker-reinforced composites exhibited apparent exponent s of 9.4-17.1 and 11.5-18.2, and apparent activation energies of 482 and 53 3 kJ/mol, respectively. Moreover, a critical strain rate was observed in bo th reinforced and unreinforced 2124Al alloys, below which the creep resista nce of the composites was higher than that of the unreinforced 2124Al alloy . Above this value, the 2124Al alloy was more creep resistant than the comp osites. An increase in the critical strain rate with increasing temperature was observed. Several established models were used to rationalize the cree p data for the composites. The creep data for both particulate and whisker- reinforced composites at 623 and 673 K can be satisfactorily interpreted by the substructure-invariance model with a stress exponent of 8, whereas tho se at 573 K cannot be reasonably rationalized by a stress exponent of 5 or 8. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.