Effect of Heat Treatment of a Melt on the Structure and Properties of the Corresponding Crystalline Ingots or Castings

Abstract: The modern concepts of the structure of liquid metals and alloys are considered. Several types of microinhomogeneity and microheterogeneity are shown to exist in liquid metal solutions. Their structural state changes as a result of variations in composition, history, temperature, and pressure or the influence of various external actions. Upon subsequent cooling at an appropriate rate, these changes can persist up to liquidus and affect the structure and properties of the solidified alloy. The main attention is paid to the influence of the heating temperature of a liquid metal. For aluminum-based alloys, the possibility of developing the optimum heat-treatment conditions for melting using the results of studying the structure and properties of melts has been shown. This optimized heat treatment of melts is shown to be an effective method to improve the quality of alloys. © 2020, Pleiades Publishing, Ltd

ВЛИЯНИЕ УСЛОВИЙ КРИСТАЛЛИЗАЦИИ НА СТРУКТУРУ И МОДИФИЦИРУЮЩУЮ СПОСОБНОСТЬ Al–Sc-СПЛАВОВ

The study covers the impact of thermo-time processing and cooling rate of molten metal on the crystallization regularities, structure, properties and modifying ability of Al–Sc alloys. The Al–Sc alloys obtained by electrolysis in the KF–NaF–AlF3–Sc2O3 melts at 820–850 °C were used as an initial charge for casting. It was found that changes in overheat values and casting temperatures make it possible to vary the shape, number and size of crystals in a wide range. The modifying effect of the cast and fast-quenched master alloys and alloy produced by electrolysis was tested on Al–4,5%Cu alloys. The greatest refinement of the Al–4,5%Cu–0,4%Sc alloy structure was obtained with the fast-quenched master alloy.Исследовано влияние режимов термовременной обработки и скорости охлаждения металлических расплавов на закономерности кристаллизации Al–Sc-сплавов, их структуру, свойства и модифицирующую способность. В качестве исходной шихты для литья использовали отливки Al–Sc-сплавов, полученные электролизом солевых расплавов KF–NaF– AlF3–Sc2O3 при 820–850 °С. Установлено, что, меняя величину перегрева расплава и температуру литья, можно в широких пределах варьировать форму, количество и размеры кристаллов. Модифицирующее действие литой и быстрозакаленной лигатур, а также лигатурного сплава, полученного электролизом, протестировано на сплавах Al–4,5%Cu. Наибольший эффект измельчения структуры сплава Al–4,5%Cu–0,4%Sc был достигнут при использовании быстрозакаленной лигатуры

Effect of Heat Treatment of a Melt on the Structure and Properties of the Corresponding Crystalline Ingots or Castings

International audienc

Effect of Heat Treatment of a Melt on the Structure and Properties of the Corresponding Crystalline Ingots or Castings

International audienc

Disperse structure forming in rapidly quenched Al-Hf alloy

Thr structure of the Al-1.4 wt.% Hf alloy was investigated depending on overheating initial melt above liquidus and cooling rate at solidification. It was shown that varying melt overheating, one can control cost structure formation. The most disperse structure forms at the temperature slightly below 1470 K. According to results of viscosity measurements, the last temperature corresponds to irreversible homogenization of the melt. It was discovered that overheating the melt above its homogenization tempeature results in grain coarsening, appearance of spherulite-like and dendrite forms of solid phase growth and formation of metastable alpha -solid solution abnormally over-saturated by hafnium. (C) 2001 Elsevier Science B.V. All rights reserved

Disperse structure forming in rapidly quenched Al-Hf alloy

Thr structure of the Al-1.4 wt.% Hf alloy was investigated depending on overheating initial melt above liquidus and cooling rate at solidification. It was shown that varying melt overheating, one can control cost structure formation. The most disperse structure forms at the temperature slightly below 1470 K. According to results of viscosity measurements, the last temperature corresponds to irreversible homogenization of the melt. It was discovered that overheating the melt above its homogenization tempeature results in grain coarsening, appearance of spherulite-like and dendrite forms of solid phase growth and formation of metastable alpha -solid solution abnormally over-saturated by hafnium. (C) 2001 Elsevier Science B.V. All rights reserved