Optimization of composition and properties of heat-resistant complex-alloyed aluminum alloy castings

Heat-resistant aluminum alloys are the high demand for a knowledge-based economy, because the development of new technology, operating at high temperatures, requires new casting alloys with high characteristics of heat resistance and light weight. Aluminium alloys belong to such group, including the most heat-resistant Al – Cu – Mn alloys (AM5 alloys). However, alloys of this system have low casting properties, which complicates the obtaining of complex shape thin-walled castings. Furthermore, during the prolonged operation at the temperatures of 250 oC and higher, this system alloys soften. The third serious deficiency of AM5 alloys (this also applies to a common type of silumin AK7ch (АК7ч) / AK9ch (АК9ч)) is a heat treatment of castings, including quenching (usually T6 and T7), which greatly affects the weaking of mechanical properties. This complication in the behavior of alloys requires the new solutions, such as a search for new original compositions based on eutectic doped with transition metals. As a result, the AN4Mts2 (АН4Мц2) alloy was developed on the basis of eutectics (Al) + Al3Ni. The analogue alloys of this type are called “nicalins”. The results of comparison of AN4Mts2 nicalin characteristics with the most heat-resistant industrial analogues (alloys on the basis of Al – Cu system and piston silumines) showed its higher long-term strength properties at the temperatures of 300–350 oC. Because of the high quality requirements of the charge and the high content of nickel, AN4Mts2 alloy can be considered as a model composition because its production requires high purity aluminum. Later a new heat-resistant nicalin AN2ZhMts (АН2ЖМц) was developed on the basis of Al – Ni – Fe – Mn – Zr system, where iron is the alloying component. Nevertheless, there are some unsolved problems: the optimal concentration of alloying elements is not defined in the developed alloy (including iron and impurities); conditions of obtaining of shaped castings with increased silicon content are not investigated; heat treatment regimes are not optimized. The information presented in this paper work is aimed at these problems' solving. This work was carried out on the basic agreement and in a creative collaboration between the engineering center of National University of Science and Techcology “MISIS” and the Research and Education Center “NANO” Far Eastern Federal University.

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