A Series of Zr-Based Bulk Metallic Glasses with Room Temperature Plasticity.

Yongyi Peng,Hong Wu,Dawei Ding,Yun Luo,Guojun Zhou,Anhui Cai,Yong Liu,Weike An

doi:10.3390/ma9060408

Yongyi Peng, Hong Wu + Show 6 more

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https://doi.org/10.3390/ma9060408

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Abstract

A group of plastic Zr-Al-Ni-Cu bulk metallic glasses (BMGs) with low Zr content was developed and their thermal and mechanical properties were investigated. The results show that these Zr-based BMGs have a single crystallization event for all heating rates in the studied temperature region. The glass transition temperature Tg decreases with increasing Zr content for all heating rates. There are two melting procedures for the BMGs whose Zr content is less than 52 at %, while three melting procedures for the other Zr-based BMGs. The second melting procedure is split into two melting procedures for Zr52.5Al12.2Ni12.6Cu22.7 and Zr53Al11.6Ni11.7Cu23.7 BMGs, while the first melting procedure is split into two melting procedures for the other BMGs. The activation energy decreases with increasing sensitivity index β for the studied Zr-based BMGs. The plastic strain εp is in the region of 0.2%–19.1% for these Zr-based BMGs. Both yield strength σy and fracture strength σf are smallest for Zr55Al8.9Ni7.3Cu28.8 BMG whose εp is largest among all studied Zr-based BMGs and reaches up to 19.1%. In addition, the mechanism for the large difference of the plasticity among the studied Zr-based BMGs is also discussed.

Highlights

Zr-based bulk metallic glasses (BMGs) have been extensively investigated due to their high glass forming ability (GFA), large compositional region for glass formation, good thermal stability, and high strength [1,2,3,4,5,6,7,8,9,10]
The studied Zr-Al-Ni-Cu BMGs can be cast into at least Φ8 mm and has a single crystallization
The studied Zr-Al-Ni-Cu BMGs can be cast into at least Φ8 mm and has a single crystallization event for all heating rates in the studied temperature region

Summary

Introduction

Zr-based bulk metallic glasses (BMGs) have been extensively investigated due to their high glass forming ability (GFA), large compositional region for glass formation, good thermal stability, and high strength [1,2,3,4,5,6,7,8,9,10]. Room-temperature plasticity is one of important requirements for the engineering applications of the BMGs. Majority of Zr-based BMGs are room-temperature brittle good room-temperature plasticity could be achieved through compositional design [3,4,5,6,7,8,9,10], minor addition [13], cold-rolling [14,15]. Critical diameter (dc ) for the formation of amorphous state is another crucial factor for engineering applications of the BMGs. increasing efforts have claimed that there is a discrepancy between the plasticity and the dc for the BMG [17]. The Materials 2016, 9, 408; doi:10.3390/ma9060408 www.mdpi.com/journal/materials

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