Structure and mechanical properties of welds of Al―Cr―Fe―Ti аlloys with quasicrystalline phase

Abstract

The structure and mechanical properties of strips from Al₉₄Fe_2.5Cr_2.5Ti alloy, made without sintering, by extrusion of powders obtained by spraying the melt by high pressure water in pre-evacuated and sealed capsules were studied. It was shown that the structure of these bands is characterized by the presence of nanocasic crystals and nanoscale grains of the aluminum matrix. The obtained strips were welded by the friction method with stirring. As a result of phase-structural studies, it was found that during friction welding with stirring of the Al₉₄Fe_2.5Cr_2.5Ti₁ nanosquasicrystalline aluminum alloy, a uniform mixture of matrix grains with quasicrystal particles is formed in the weld. It is shown that in the zone of thermomechanical impact at the interface between the weld and the main material during the welding process, the directions of the strip fibers are reoriented due to plastic deformation caused by rotational and translational movement of the friction welding tool. The hardness of the main material of the strip and the zone of the welded joint, after the applied welding modes practically do not differ. Moreover, due to the formation of a more uniform structure, the hardness of the weld is slightly higher. The strength of the welded joint at room temperature is 370 MPa, and at a test temperature of 300 °C ― 170 MPa. The destruction of the welded joint at room temperature occurs in the transition zone and the zone welded joint, and at 300 °C ― in the seam zone. It is shown that the method fo rproducing permanent joints by friction with stirring is promising for the production of welded structures from aluminum alloys, which are strengthened by nanosized metastable quasicrystals, since it allows you to save the quasicrystalline structure of the strengthening particles in the seam. Full text download