Effect of Zr on Microstructure and Mechanical Properties of the Al–Cu–Yb and Al–Cu–Gd Alloys

Olga Mamzurina,Sayed Amer,Ruslan Barkov,Maria Glavatskikh,Andrey Mochugovskiy,Andrey Pozdniakov,Irina Loginova

doi:10.3390/met12030479

Abstract

The effect of zirconium on the microstructure, phase composition, and mechanical properties of AlCuYb and AlCuGd alloys was studied. The microstructure of the as-cast alloys did not consist of new intermetallic phases of zirconium with other elements, so the zirconium was fully dissolved in the aluminum matrix. The AlCuYbZr/AlCuGdZr alloys demonstrated higher hardness values compared to the AlCuYb/AlCuGd alloys due to the precipitation of the Al3(Zr,Yb) and Al3(Zr,Gd) phases, which were formed during the homogenization treatment. The AlCuYbZr alloy had a 10–20 MPa higher yield and tensile strength than the AlCuGdZr alloy at the same annealing temperature and time. The AlCuYbZr alloy exhibited good mechanical tensile properties at an annealing temperature of 100 °C for 1 h, with a yield strength of 276 MPa, ultimate tensile strength of 312 MPa, and elongation of 3.1%, while the as-rolled AlCuGdZr alloy had similar mechanical tensile properties, with a yield strength of 279 MPa, ultimate tensile strength of 307 MPa, and elongation of 4.8%. At an annealing temperature of 300 °C for 10 min, The AlCuYbZr and AlCuGdZr alloys showed a good ductility of 10.5% and 8%, respectively, with 207 MPa yield strength for both alloys. AlCuYbZr and AlCuGdZr alloys are a prospective base composition for developing novel high technology heat resistant aluminum alloys.

Highlights

One of the major aluminum alloy systems with precipitation hardening is the aluminumcopper systems with strengthening from CuAl2 [1]
AlCuYbZr and AlCuGdZr alloys were prepared by casting metallurgy in an electric resistance furnace
The AlCuYbZr and AlCuGdZr alloys were homogenized at different times before Figure 4

Summary

Introduction

One of the major aluminum alloy systems with precipitation hardening is the aluminumcopper systems with strengthening from CuAl2 [1]. The mechanical properties of Al–Cu alloys are highly dependent on the parameters of the precipitates, such as the lattice structure, number density, shape, and size and distribution of the particles [2]. Al–Cu alloys have a high strength at room and elevated temperatures [1,3]. The high heat resistance of the Al–Cu alloys provides thermal stability to the θ’ (Al2Cu) precipitates [2,3]. Cast Al–Cu alloys generally have a coarse grain structure, inhomogeneous intermetallic phases, and low castability. A coarse structure causes stress concentration and acts as premature crack initiation in tension. Improvement of the mechanical and casting properties can be achieved, for example, by heat and ultrasonic treatment, alloying, and grain refinement [4]

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