Abstract: A cast aluminum alloy containing up to about 0.35% by weight chromium is heated to a first elevated temperature to homogenize the casting and dissolve the chromium content in an aluminum-based matrix phase. The alloy is then heated at a lower elevated temperature to cause the precipitation of a portion of the chromium as an aluminum-containing and chromium-containing intermetallic compound. A suitable amount of chromium is retained in solid solution in aluminum. Thus, the concentration of dissolved chromium in an aluminum alloy may be controlled to fall within specified ranges which result in improvements in both the strength and ductility of the alloy. Impurity amounts of iron may also be precipitated as intermetallic particles from the aluminum matrix to enhance the ductility of the aluminum-based alloy.

Abstract: A cast aluminum alloy containing up to about 0.35% by weight chromium is heated to a first elevated temperature to homogenize the casting and dissolve the chromium content in an aluminum-based matrix phase. The alloy is then heated at a lower elevated temperature to cause the precipitation of a portion of the chromium as an aluminum-containing and chromium-containing intermetallic compound. A suitable amount of chromium is retained in solid solution in aluminum. Thus, the concentration of dissolved chromium in an aluminum alloy may be controlled to fall within specified ranges which result in improvements in both the strength and ductility of the alloy. Impurity amounts of iron may also be precipitated as intermetallic particles from the aluminum matrix to enhance the ductility of the aluminum-based alloy.

Abstract: A method and apparatus for precisely controlling plastic strain rate during plastic deformation testing of a solid material such as a metal or plastic are described in which the effects of elastic strain rates associated with the specimens and machines used for such testing are eliminated by applying corrections proportional to the load on the specimen. Thus strain rate sensitivity, unaffected by the machine or specimen modulus can be measured. Strain rate sensitivity can be used to measure the activation volume of the specimen which may be used for quality control of material processing and/or manufactured articles.