The modification of hypereutectic high-alloy silumins — prospects for the development of technology for producing materials with a low linear expansion coefficient

Abstract

This article discusses the possibilities of using hypereutectic silumins and the problems that impede their wider distribution. The known methods of manufacturing products from hypereutectic silumins of high quality are shown. A method for producing casting blocks from hypereutectic silumins by direct chill casting is considered. The possibility of milling primary silicon crystals by introducing modifiers and master alloys of Al-Si-P, Al-Cu-P systems, inorganic carbon and phosphorus compounds is shown. The tendency of copper-doped silumins to hot shortness is shown. The technology of impact on the melt of ultrasonic cavitation is considered together with the introduction of additional active modifiers made of master alloy rods to obtain casting blocks from hypereutectic high-alloy silumins using the method of direct chill casting with a primary silicon crystal size of no more than 10 µm. Technological principles for reducing the grain size of α-solid solution, uniformly distributed over the ingot cross-section, are proposed.