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

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 1h, 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.

Effect of Mn/Ag Ratio on Microstructure and Mechanical Properties of Heat-Resistant Al-Cu Alloys

“…After solution–aging, the fine and dispersed θ′-Al 2 Cu metastable phase precipitates in the Al-Cu alloy matrix, which has a semi-coherent relationship with the matrix and can effectively block dislocation movement and pin grain boundaries, thus improving the high-temperature strength and creep resistance of the alloy [ 6 , 7 ]. For Al-Cu alloys, the rich microstructure of θ′-Al 2 Cu provides the best strength and thermal stability for high-temperature applications [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. θ′-Al 2 Cu has a four-angle distorted fluorite structure (space group I4/MMM) where a = 0.404 nm and C = 0.580 nm.…”