High Strength Al-La, Al-Ce, and Al-Ni Eutectic Aluminum Alloys Obtained by High-Pressure Torsion.

Stanislav O Rogachev,Adrian V Zavodov,Evgeniya A Naumova,Vladimir M Khatkevich,Eva A Lukina

doi:10.3390/ma14216404

Stanislav O Rogachev, Adrian V Zavodov + Show 3 more

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https://doi.org/10.3390/ma14216404

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Abstract

A comparative analysis of the effect of high-pressure torsion (HPT) on the microstructure and tensile properties of the Al–10% La, Al–9% Ce, and Al–7% Ni model binary eutectic aluminum alloys is carried out. An HPT of 20-mm diameter specimens in as-cast state was carried out under constrained conditions, at room temperature, pressure P = 6 GPa, and number of turns N = 5. It is shown that the formation of nano- and submicrocrystalline structures and the refinement of eutectic particles in aluminum alloys simultaneously provide a multiple increase in strength while maintaining a high plasticity margin. This combination of properties has been achieved for the first time for severely deformed binary aluminum eutectics. The relationship between the type of eutectic particles, the structure formation process and the mechanical properties of the aluminum alloys has been established. The thermal stability of severely deformed aluminum alloys at heating up to 200 °C has been studied.

Highlights

An urgent task is the creation of high-tech aluminum alloys with increased mechanical and special physical properties, for example, a low temperature coefficient of linear expansion, increased wear resistance and/or increased strength at elevated temperatures [1]
The high-pressure torsion (HPT)-deformation of all aluminum alloys leads to a significant increase in the values of microhardness and to the appearance of inhomogeneity of their distribution over the specimen diameter: the minimum values of microhardness were observed in the center of the specimen, and the maximum values were observed at its periphery (Figure 1)
Based on the results of studying the effect of the HPT process (20-mm diameter specimens, N = 5, P = 6 GPa) on the microstructure and tensile mechanical properties of the Al–10% La, Al–9% Ce, and Al–7% Ni as-cast model binary eutectic aluminum alloys, the following conclusions were drawn: (1) The HPT-deformation leads to the formation of nano- and submicrocrystalline structures in the Al–10% La and Al–9% Ce alloys and a submicrocrystalline structure in the Al–7% Ni alloy with a relatively low density of dislocations inside the crystallites, as well as to the eutectic particle refinement in all alloys

Summary

Introduction

An urgent task is the creation of high-tech aluminum alloys with increased mechanical and special physical properties, for example, a low temperature coefficient of linear expansion, increased wear resistance and/or increased strength at elevated temperatures [1]. The multicomponent eutectic alloys based on the systems such as aluminum–calcium (light, corrosion-resistant), aluminum–cerium and aluminum–lanthanum (heat-resistant), aluminum–nickel (highstrength and heat-resistant) are very promising for practical use [2,3,4,5,6]. These alloys are highly technological in casting, since they have narrow crystallization intervals, and they are deformed in the annealed state, despite the large fraction (over 10% by volume) of intermetallic phases in the structure. It is of practical interest to increase the strength properties of base eutectic alloys without additional alloying (which leads to a decrease in technological properties and an increase in the cost of alloys), which expands the scope of their use in modern technology

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