Ultrafine shape memory alloys synthesized using a metastable metallic glass precursor with polymorphic crystallization. (March 2021)

• Record Type: Journal Article
• Authors: Hong, Sung Hwan; Park, Hae Jin; Song, Gian; Liaw, Peter K.; Kim, Ki Buem
• Is Part Of: Applied materials today. Volume 22(2021)
• Publication Date: 2021-03
• Subjects: Metallic glass precursor -- Crystallization kinetics -- Shape memory alloy -- Superelastic effect -- Shape memory effect; Materials science -- Periodicals; Materials -- Research -- Periodicals; 620.1105
• DOI: 10.1016/j.apmt.2021.100961
• Languages: English
• ISSNs: 2352-9407

Abstract

Highlight: Ni–Ti–Cu–Zr metallic glass precursor is designed with consideration of amorphous-to-crystalline transition and glass forming ability. The Ni45 Ti40 Cu5 Zr10 metallic glass crystallizes into ultrafine-structured shape memory alloy consisted of single B2 phase. Isothermal annealing temperature significantly influences crystallization kinetics, i.e. nucleation and growth rates, and the grain size exponentially increases with an increase of annealing temperature. The ultrafine-structured shape memory alloys fabricated by using metallic glass precursor reveal the excellent superelastic and shape memory effects. This study provide a feasibility of the simple fabrication processing for ultrafine shape memory alloys by one-step heat-treatment technique. Abstract: Metallic glasses have been considered as a precursor for developing nano- or ultrafine-structured alloys based on its crystallization behavior at large undercooled liquid state. However, the multicomponent system, requiring high glass-forming ability, makes it difficult to control the crystallization mechanism, and leads to the formation of brittle intermetallic compounds during crystallization. Here, we present an intermetallic-type metallic glass precursor designed via thermodynamic and physical considerations. The metallic glass precursor polymorphically crystallized into ultrafine-structured single-phase shape memory alloy. The crystallization kinetics and final grain-size strongly depend on isothermal annealing temperatures. The shape memory alloys fabricated using the metallic glass precursor revealed excellent superelastic and shape memory effects, which was affected by the critical stress for martensitic transformation depending on the grain size. Our approach and discovery provide a feasibility of the simple fabrication processing for ultrafine-structured shape memory alloys by one-step heat-treatment technique including thermoplastic forming of metallic glass precursor. Graphical abstract: Image, graphical abstract