Deformation behavior of a TiZr-based metallic glass composite containing dendrites in the supercooled liquid region

The deformation behavior of a TiZr-based bulk metallic glass composite(BMGC)was characterized in the supercooled liquid region(SLR)from 623 K to 693 K.It was observed that the alloy exhibits the deformation behavior from work softening at low temperatures to work hardening at high temperatures.The yield stress and overshoot stress decrease remarkably with the increase of temperature,accompanied by superplasticity.The results showed that the crystallization occurred in the amorphous matrix for the post-deformation samples and the volume fraction of the corresponding crystallization products increased with increasing testing temperature.It is implied that the work hardening behavior was closely associated with the crystallization of the amorphous matrix.The tensile stress can accelerate the crystallization of amorphous matrix and the martensitic transformation of dendrite phases,which implies that the thermal stability of the alloy decreases under tension.These findings shed light on designing new BMGCs with high mechanical performance as well as the good SLR formability.

Corrosion mechanisms of Zr-based bulk metallic glass in NaF and NaCl solutions

So far,some investigations related to the corrosion mechanism of Zr-based metallic glasses in solutions containing Cl-have been developed.However,few attentions have been paid to the situation in F--containing solution.This paper describes the corrosion behaviours of Zr52Al10Ni6Cu32 bulk metallic glass(BMG)in Na F and Na Cl aqueous solutions.The corrosion mechanism of Zr-based BMG in F–containing solution was proposed for the first time.It was found that in Na Cl solutions,Zr-based BMG samples underwent typical pitting corrosion.Selective dissolution of Zr,Al and enrichment of Cu were observed in corrosion pits.However,corrosion occurred in the form of general breakdown of passive film in Na F solutions.Such difference is interpreted in terms of the binding ability of anions to surrounding molecules,i.e.,Cl-with loose surrounding water passes through the passive film to cause pitting;F-with a tight surrounding molecules layer absorbs on passive film then coordinates with cations from matrix.