Effect of Deformation Temperature on the Stage IV Deformation in <100> Oriented Aluminum Single Crystal

Abstract

It is known that at room temperature the tensile stress-strain curve of an aluminum single having <100> tensile orientation becomes flat after about a two percent elongation. (This flat region of the stress-strain curve is named Stage IV). In the previous paper, the propagation of a clustered slip accompanied by a prominent cross slip was observed in the Stage IV region of curve. In the present study, <100> oriented aluminum single crystals were tested in tension at various temperatures so as to clarify the influence of temperature on the deformation mechanisms in Stage IV. At 203K, a few clustered slip lines accompanied by a prominent cross slip occurred, but they did not propagate in the entire region of the specimen. The stress-strain curve became flat only from about a ten percent elongation. In the crystal stretched at 77K, the cluster did not propagate at all from either end of the specimen, and so the stress-strain curve did not become flat. On the other hand, a wavy coarse slip was observed and the curve became flat from about a 0.5 percent elongation at 473K. It was suggested that these wavy slip lines were produced by a frequent repetition of the cross slip on two {111} planes and also possidly on a {110} plane having the same slip direction. It was confirmed that the occurrence of Stage IV is caused by the of the clustered slip accompanied by a prominent cross slip, and is much influenced by the temperature of deformation due to the easiness of the cross slip.