On cryothermal cycling as a method for inducing structural changes in metallic glasses

• Published in: NPG Asia materials 2018-04, Vol.10 (4), p.137-145
• Main Authors: Ketov, Sergey V., Trifonov, Artem S., Ivanov, Yurii P., Churyumov, Alexander Yu, Lubenchenko, Alexander V., Batrakov, Alexander A., Jiang, Jing, Louzguine-Luzgin, Dmitri V., Eckert, Jurgen, Orava, Jiri, Greer, Alan Lindsay
• Format: Article
• Language: English
• Subjects: 140/146; 639/301/1023/218; 639/301/930/1032; Amorphous materials; Atomic structure; Biomaterials; Chemical bonds; Chemistry and Materials Science; Composition; Cycles; Energy Systems; Heterogeneous structure; Materials Science; Mechanical properties; Metallic glasses; Modulus of elasticity; Optical and Electronic Materials; Spatial distribution; Structural Materials; Surface and Interface Science; Thin Films
• ISSN: 1884-4049; 1884-4057
• DOI: 10.1038/s41427-018-0019-4

The influence of cryothermal treatment on the mechanical properties of metallic glasses with different compositions was investigated in the present work. It was found that cryothermal cycling can induce rejuvenation as well as relaxation of the metallic glasses. The local apparent Young’s modulus and its spatial distribution width on the surface of the metallic glass increase after cryothermal cycling, while in the bulk the effect depends on the glass composition. It appeared that this increase is temporary and disappears after a period of room temperature aging. This effect is connected with a large distribution of relaxation times in the metallic glasses due to their heterogeneous structure and the formation of complex native oxides on the outer surfaces of the glasses. Our findings reveal that a cryothermal cycling treatment can improve or degrade the plasticity of a metallic glass, and the atomic bond structure appears to be very important for the outcome of the treatment. Metallic glasses: cryothermal cycling affects plasticity Cryothermal cycling affects the structure and mechanical properties of metallic glasses in ways that depend on their composition. These metallic alloys, with their disordered atomic structures, have promising characteristics but before widespread applications are possible their behavior needs to be better understood. An international team of researchers led by Sergey Ketov from the Erich Schmid Institute of Materials Science, Leoben, Austria, have now subjected three such glasses with the general formula Zr 60 Cu 20 M 10 Al 10 (where M is iron, cobalt or nickel) to temperature cycles between 77 and 320 K. The treatment was found to temporarily increase their surface stiffness, to a greater extent for the iron-based sample. It also affected their bulk plasticity: an increase was noticed for the iron-based glass, “rejuvenating” the material, whereas the cobalt-based glass was degraded and the nickel-based glass remained largely unaffected. Cryothermal cycling can induce rejuvenation as well as relaxation of metallic glasses. The surface apparent Young’s modulus and its spatial distribution width increase after the treatment, while in bulk effect depends on the glass composition. This increase is temporary and disappears after some time of room temperature aging. Effect is connected with a large distribution of relaxation times in metallic glasses due to their heterogeneous structure and the formation of complex native oxide on th