Development of creep-resistant casting alloys based on the Al-Fe-Mn-Ni system

Abstract

Development of new creep-resistant materials is a constantly existing task for modern materials science. At the same time, the creation of creep-resistant aluminum alloys plays an important role due to the combination of low density and the potential to achieve high resistance to properties degradation unter elevated temperatures. Increasing the level of operating temperatures for aluminum alloys makes it possible to replace some of the parts made of iron-based materials in cars, airplanes and various machinery. This will allow to reduce the weight of machines and mechanisms, increase their energy efficiency and environmental friendliness due to the reduction of carbon dioxide emissions.
Most of the widely used creep-resistant aluminum alloys belong to the Al-Si-Cu, Al-Cu and Al-Si-Cu-Fe-Ni systems. Such alloys have a relatively low level of mechanical properties, which is insufficient for modern requirements. Their significant advantage is the ease of obtaining finished products by using casting processes. Among the alternative systems of heat-resistant aluminum alloys, those containing Fe, Ni, Cr and Mn are often considered.
Iron and nickel are able to form fibrous nano-sized components of eutectics with aluminum, which are stable at high temperatures. They are effective barriers for the movement of dislocations and they also do not eliminate alloys plasticity. The disadvantage of such alloys is the zero alloying of the matrix metal, which means potentially low strength.
Alloying of heat-resistant aluminum alloys should be carried out with elements that have a low diffusion coefficient in aluminum. The best option for this is manganese, which can dissolve in Al-matrix in a large quantities and forms a stable strengthening intermetallic Al₆Mn with aluminum. Al-Fe-Mn-Ni alloys, because of their structural and phase features, can be subjected to plastic deformation,
which, in combination with heat treatment, significantly increases the level of mechanical properties of alloys in a wide temperature range due to grain refinement and inhibition of recrystallization by stable ultradispersed intermetallic particles.