Effect of the eutectic Al-(Ce,La) phase morphology on microstructure, mechanical properties, electrical conductivity and heat resistance of Al-4.5(Ce,La) alloy after SPD and subsequent annealing

• Published in: Journal of alloys and compounds 2019-08, Vol.796, p.321-330
• Main Authors: Medvedev, Andrey E., Murashkin, Maxim Y., Enikeev, Nariman A., Bikmukhametov, Ilyas, Valiev, Ruslan Z., Hodgson, Peter D., Lapovok, Rimma
• Format: Article
• Language: English
• Subjects: Alloys; Aluminum base alloys; Annealing; Atom probe tomography; Cerium; Dislocation density; Earth surface; Electrical conductivity; Electrical resistivity; Heat resistance; High-pressure torsion; Intermetallic particles; Lanthanum; Mechanical properties; Mechanical strength; Morphology; Plastic deformation; Rare earth; Solid solutions; Spheroidizing; Surface area; Tensile stress; Thermal resistance; Thermal stability; Ultrafines
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.05.006

This paper reports on a crucial role of the morphology of intermetallic Al11RE3 phase and Al/Al11RE3 interphase (where RE – Rare Earth) surface area, before plastic deformation, on the electrical and mechanical properties and the thermostability of aluminium alloys. Cast Al-4.5 (Ce + La) alloy samples, processed with and without spheroidization treatment (ST), were subjected to high pressure torsion (HPT) at room temperature (RT) followed by annealing at 230 °C, 280 °C and 400 °C for 1 h. It is demonstrated, that the changes of initial alloy structure (particles shape/size) and the decrease of interphase surface area affect the distribution of intermetallic particles after HPT, the distribution of ultrafine grains and the dislocation density, as well as the formation of a supersaturated solid solution of Ce and La in aluminium. The optimal combination of strength (ultimate tensile stress (σUTS) 430 MPa) and conductivity (55.9% International Annealed Copper Standard, IACS) was obtained after ST, HPT and an annealing temperature of 230 °C. [Display omitted] •Influence intermetallic morphology on structure and properties of Al alloys is studied.•The alloys were subjected to severe plastic deformation in different initial state.•HPT of Al-4.5(Ce,La) alloy results in supersaturated solid solution formation.•Application of pre-HPT heat treatment prevents the solid solution formation during HPT.•The diffusion of Ce and La in Al is provided by extra vacancy concentration.