High-temperature creep behaviour of powder-metallurgy aluminium compositesreinforced with SiC particles of various sizes

Tensile creep tests have been performed at 573-673 K on pure aluminium and aluminium-based composites reinforced with SiC par-tides of different sizes (3.5, 10 and 20 mu m) fabricated by powder-metallurgy (PM) techniques. Bot h the pure aluminium and the composites exhibited high values of the appare nt stress exponent (14.3-26.1) and creep activation energy (253-261 kJ/mol) . The results showed that the creep rate of composites reinforced with smal l particles (3.5 mu m) was two-three orders of magnitude lower than that of pure aluminium. However, the creep resistance of composites reinforced wit h large SiC particles (10 and 20 mu m) was essentially identical to that of pure aluminium. Various creep models were attempted to rationalize the cre ep data of pure aluminium and particulate composites. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.