Showing papers on "Equiaxed crystals published in 1974"

Grain refinement of copper alloys by phosphide inoculation

Abstract: A method of refining as-cast grain size of copper alloys by inoculation of the melt, prior to or during pouring, by addition of phosphorus and a transition metal such as zirconium. Certain parameters of the inoculation and casting process are critical. In particular, the melt with a P content of 0.002 to 1.0% is stirred at 20* to 200*C above the liquidus, then 0.002 to 0.5% of a transition metal such as Zr is stirred into the melt, and finally within a period of 10 minutes or less, the alloy must be poured and solidified. Through the synergistic action of P and Zr, the resulting cast ingot is then characterized by advantages such as improved uniformity, absence of columnar crystals, and finer equiaxed grains, which help prevent difficulties in further processing of the alloy.

Method of continuous casting using linear magnetic field for core agitation

Abstract: A continuous casting method for the production of a casting having a solidified metallic structure which is nearly all composed of equiaxed crystal uniformly distributed, by agitating the crater of the cast object during the process of solidification by applying a travelling electromagnetic field to an extent sufficient to make the velocity vector of the main flow of the agitated molten metal present in the plane perpendicular to the direction of withdrawing the cast object and to confine the entire flow in such crater within the limited agitation zone, and an apparatus for carrying out the method.

Strength and Microstructure of Dense, Hot-Pressed Silicon Carbide

Abstract: The microstructural and strength characteristics of dense SiC, hot-pressed from submicron SiC powders with small additions of boron, are shown to be strongly dependent on the control exercised over oxygen content during pressing. Uniform, equiaxed grain structures of SiC are obtained if sufficient oxygen is present to allow detectable particles of SiO2, whereas uniform, elongated grain structures of β SiC are obtained if excess carbon is utilized to reduce oxygen content to undetectable limits. At intermediate oxygen levels, free silicon was formed and large, tabular α-SiC grains in a fine-grained β-SiC matrix were obtained.

The Columnar-Equiaxed Change in Superpure Aluminium Containing Transition-Metal Additions

Abstract: The columnar-equiaxed transition in superpure aluminium requires not only the presence of nucleants or crystal fragments, but also fulfilment of the conditions for growth on these particles ahead of the solid interface. Experimental evidence emphasizing these factors is presented.

Method for preparing superconductors

Abstract: A superconductor having an equiaxed fine grain beta-tungsten crystalline structure found to have improved high field critical current densities is prepared by sputter-depositing superconductive material onto a substrate cooled to below 200° C. and heat-treating the deposited material.