Abstract: A method is provided for obtaining uniform grain growth within .gamma.' precipitation strengthened nickel-base superalloys. The method includes forming a billet having a very fine grain size in order to achieve optimum superplasticity of the superalloy during forging. The article is then heated to a pre-working hold temperature in a manner which prevents coarsening of the microstructure and a loss of superplasticity. The article is then worked, such as by forging, at a temperature below the .gamma.' solvus temperature of the alloy, so as to maintain local strain rates within the article below a critical strain rate for random grain growth, and so as to maintain the strain rate gradient throughout the article below a critical upper limit. After working, the article is subjected to annealing at a temperature which is less than the .gamma.' solvus temperature of the alloy, and for a duration which is sufficient to remove accumulated metallurgical strain in the article.

Abstract: The present invention provides a process for the preparation of YBa.sub.2 Cu.sub.3 O.sub.7-x superconductor which comprises surrounding a sintered material in which the molar ratio of Y:Ba:Cu is 2:1:1 with liquid-forming powder and subjecting the powder compact to isothermal heat-treatment at a temperature below the peritectic temperature of YBa.sub.2 Cu.sub.3 O.sub.7-x. The YBa.sub.2 Cu.sub.3 O.sub.7-x superconductors prepared according to the present invention have aligned grain structure in one direction and thus exhibit a high critical current density.

Abstract: MoO.sub.2 is used as an accelerant for transformation of zirconia (ZrO.sub.2) from a tetragonal to a monoclinic crystal phase. A ZrO.sub.2 -MoO.sub.2 alloy having an increased content of monoclinic ZrO.sub.2 is prepared by mixing MoO.sub.2 with ZrO.sub.2 followed by heat treatment. In another aspect of the invention, the surface of an alumina-zirconia composite is strengthened by heating the composite in the presence of MoO.sub.2 -ZrO.sub.2 mixed powder.