Free volume in Zr-based bulk glassy alloys studied by positron annihilation techniques

Ishii, Akito; Iwase, A.; Yokoyama, Yoshihiko; Konno, Toyohiko J.; Kawasuso, Y; Yabuuchi, Youichi; Maekawa, M.; Hori, Fuminobu

doi:10.1088/1742-6596/225/1/012020

Cited by 7 publications

(1 citation statement)

References 11 publications

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“…Generally, thermally activated STZs initiate around free-volume sites under an applied shear stress because high elastic strain at free-volume sites energetically promotes STZ formation. From the studies on the positron annihilation analysis of Zr-Cu-Al BMGs, free volume in ternary hypoeutectic Zr 60 Cu 30 Al 10 BMG is surrounded by a higher fraction of Zr atoms as compared to the eutectic Zr 50 Cu 40 Al 10 BMG, which indicates that the higher fraction of Zr-Zr atomic pairs in this alloy is probably accompanied with more free volume [24]. Moreover, it is previously reported that a large compressive plastic strain could be achieved due to a large amount of randomly distributed free volume induced in Zr-Cu-Al-Ti BMG system by Ti minor alloying [25].…”

Section: Resultsmentioning

confidence: 99%

Effects of Zr Content on the Bending Property and Crystallization Behavior of Ductile Zr-Based Bulk Metallic Glasses

Hua

Chen

Liao

2018

MSF

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In this study, the effects of Zr content on the bending property, non–isothermal and isothermal crystallization kinetics of high–Zr–based BMGs were investigated. The BMGs exhibit high bending strength and their bending plasticity enhances with increasing Zr content, which is due to more free volume with high–Zr–content. During continuous heating, the crystallization phases for Zr66 and Zr70 BMGs are Zr2Cu and Zr2Ni phases. Zr70 alloy exhibits the highest activation energies for glass transition and crystallization because of the sluggish diffusion of large Zr atoms. Under isothermal condition, the average Avrami exponent of Zr66 alloy modeled by the JMA equation is about 2.6, implying a diffusion–controlled three dimensional crystallization growth with an increasing nucleation rate. The average Avrami exponent of 2.0 for Zr70 alloy indicates a diffusion–controlled three dimensional crystallization growth with a decreasing nucleation rate, which can be attributed to its higher activation energy for crystallization.

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Section: Resultsmentioning

confidence: 99%