The coupling effects of laser thermal shock and surface nitridation on mechanical properties of Zr-based metallic glass

JOURNAL OF ALLOYS AND COMPOUNDS

卷:770

Article

Huang, Hu^1,2  Jiang, Minqiang^3,4  Yan, Jiwang² 

[1] Jilin Univ, Sch Mech Sci & Engn, Changchun 130022, Jilin, Peoples R China

[2] Keio Univ, Fac Sci & Technol, Dept Mech Engn, Yokohama, Kanagawa 2238522, Japan

[3] Chinese Acad Sci, Inst Mech, State Key Lab Nonlinear Mech, Beijing 100190, Peoples R China

[4] Univ Chinese Acad Sci, Sch Engn Sci, Beijing 100049, Peoples R China

关键词: Metallic glass;    Laser irradiation;    Surface nitridation;    Hardness;    Serrated flow;    Shear band;   

DOI  :  10.1016/j.jallcom.2018.08.195

来源: Elsevier

【 摘 要 】

Laser processing is a versatile tool for applications in the field of metallic glasses (MGs). Previous studies reported that surface nitridation, i.e. the formation of ZrN phase, occurred when laser irradiation of Zr-based MG was performed in nitrogen gas. Additionally, it was reported that laser thermal shock usually softened the irradiated surface. Therefore, the coupling effects of laser thermal shock and surface nitridation on mechanical characteristics of Zr-based MG should be further clarified. For this purpose, in this study, laser irradiation of Zr-based MG was conducted under various experimental conditions, followed by evaluating the surface characteristics by X-ray diffraction (XRD), nanoindentation, and energy-dispersive X-ray (EDX) spectroscopy. Experimental results indicated that the nanoindentation hardness, serrated flow, and surface shear bands were significantly affected by laser irradiation in nitrogen gas. Both surface softening and hardening were observed which depended on the experimental conditions. A competition mechanism between laser thermal shock and the introduction of ZrN phase was employed to rationalize these results. Furthermore, the affecting layer of ZrN phase along the depth direction was measured by EDX. The obtained results suggest a new method to introduce secondary phase into Zr-based MG surface and further to tune the mechanical characteristics of MGs. (C) 2018 Elsevier B.V. All rights reserved.

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