Characteristics of stress relaxation kinetics of La60Ni15Al25 bulk metallic glass. (1st October 2015)

• Record Type: Journal Article
• Authors: Qiao, J.C.; Wang, Yun-Jiang; Pelletier, J.M.; Keer, Leon M.; Fine, Morris E.; Yao, Y.
• Is Part Of: Acta materialia. Volume 98(2015)
• Page Start: 43
• Page End: 50
• Publication Date: 2015-10-01
• Subjects: Metallic glasses -- Stress relaxation -- Mechanical properties -- High-temperature deformation -- Deformation kinetics; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2015.07.020
• Languages: English
• ISSNs: 1359-6454

Abstract

Graphical abstract: Fig. 1 shows temperature dependence of the normalized loss modulus of La60 Ni15 Al25 bulk metallic glass (heating rate: 3 K/min and driving frequency: 3 K/min): (1) As-cast, (2) annealed one (annealing temperature: 448 K and annealing time: 16 h). A pronounced β relaxation process was observed at lower temperature (∼360 K). In addition, the α relaxation was detected at a higher temperature (∼500 K). Abstract: The β relaxation typically plays an important role in the plastic deformation of glassy materials. Compared with amorphous polymers, most of the metallic glasses do not show evident β relaxation based on mechanical spectroscopy. However, La60 Ni15 Al25 bulk metallic glass (BMG) exhibits a prominent β relaxation process, which could be an ideal model alloy to investigate the correlation between the β relaxation and mechanical behavior of metallic glasses. In this work, compressive properties and stress relaxation at high temperature (below glass transition temperature Tg ) were studied. Stress relaxation of La60 Ni15 Al25 BMG was measured by uniaxial compressive tests and mechanical spectroscopy around both α and β relaxation temperature domain. At higher temperatures and sufficiently low strain rate, the flow behavior of the La60 Ni15 Al25 BMG could be simulated by a master curve, showing that the behavior is independent of temperature, especially on the proximity of the β relaxation process. Because the existence of the β relaxation, a high value of the activation volume for the plastic deformation could be ascribed to the existence of a specific atomic arrangement in the La60 Ni15 Al25 BMG. It is found that compressive stress relaxation kinetics parameter remains temperature independent below Tg .