CREEP REGIMES FOR DIRECTIONALLY SOLIDIFIED AL-AL3NI EUTECTIC COMPOSITE

Creep characteristics of Al-Al3Ni eutectic composites directionally solidified at 2.2 x 10(-2) mm/s were determined over a wide range of stress and temperature. Four distinct regions of creep were observed. The rate controlling mechanisms for the four regions appear to be high-temperature dislocation climb in the Al matrix, low-temperature climb in the Al matrix, boundary sliding, and a mechanism involving deformation of the Al3Ni fibers. Creep rates of the Al-Al3Ni composite are several orders of magnitude smaller than for pure Al, and apparently, in the regions where deformation of the Al matrix is rate controlling, only a very small fraction of the matrix is deforming during creep of the composite.