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Structure of Al-Cu Alloy Rapidly Quenched from Liquid State and Precipitation from Enforced Solid Solution

1968; Japan Institute of Metals and Materials; Volume: 32; Issue: 12 Linguagem: Inglês

10.2320/jinstmet1952.32.12_1210

1880-6880

Yasuo Fujinaga, Sigemaro Nagakura, Shigu eacute o Oketani,

Solidification and crystal growth phenomena

Ten kinds of Al-Cu alloy (0∼23.8 at%Cu) were rapidly quenched from liquid state by means of a rotating cylinder technique and the structures were investigated with X-ray and electron diffraction as well as electron microscope. Lattice parameter measurements showed that an enforced solid solution was formed beyond the solubility limit of copper in aluminum. In 18.4 at%Cu alloy the solubility was 5 at% in a thick part of the specimen and 16 at% in a thin part subjected to more rapid cooling. Electron microscopic observations suggested that an enforced solid solution with higher copper concentration may be produced in the higher copper alloys, if the cooling rate is made faster. The precipitation from the enforced solid solution was found to take place in the sequence GP→θ″→θ′→θ as in the case of precipitation from the ordinary supersaturated solid solution and that the precipitation temperature becomes lower with increasing copper content. The mechanism of precipitation seems to be essentially the same in both cases.