Creep behavior of Al-Al3Ni eutectic composites
Abstract
Specimens of Al-Al3Ni, directionally solidified at 11 cm per hr, were creep-tested at a single set of conditions to plastic strains in the first, second, and third stages, and to rupture. Specimens from these interrupted tests were sectioned and examined by transmission electron microscopy. Due to the small plastic strains encountered in the first and second stages of deformation (ε{thorn} < 0.3 pct) relatively little substructure buildup was observed in the matrix of these specimens. In specimens tested to rupture, dense dislocation cells keyed on the whiskers were found. As a result, a time-dependent fracture mechanism was identified which differed from normal tensile fracture, and was related to the substructure buildup. The effects of solidification rate on creep resistance, macrohardness, and compressive yield strength were also investigated and showed that by increasing the solidification rate a more creep-resistant, harder, and stronger material was produced. This has suggested that additional strengthening of this material by a dispersion effect of the whiskers on the matrix is possible. © 1972 The Metallurgical of Society of AIME.