Abstract
The rejuvenation behavior of an Zr50Cu40Al10 (at.%) metallic glass upon cryogenic cycling treatment has been investigated. At a high casting temperature, the microstructure of the glass is quite homogenous and thus, internal stress cannot be generated during cycling. Therefore, the glass cannot be rejuvenated by cryogenic cycling treatment. In the contrary, by lowering the casting temperature, nano-sized heterogeneity can be induced and subsequently generates the internal stress and rejuvenates the glass. Once the glass is rejuvenated, the more induced free volume can plasticize the glass with a higher plastic strain. These findings point out that the synthesis conditions can tailor the heterogeneity of the glass and subsequently affect the following rejuvenation behavior upon thermal treatment. It can also help understand the mechanisms of rejuvenation of metallic glass upon cryogenic cycling treatment.
Highlights
The bulk metallic glasses (BMGs) have attracted a lot of interests because of their superior mechanical properties such as high fracture strength and large elastic limit, which originates from their unique long-range disordered microstructures [1–3]
Similar to X-ray diffraction (XRD) results, Tg and Tx for both samples are very close, i.e., 690 K and 780 K for As-cast and 688 K and 781 K for Thermal treated with 30 cycles (DCT30), respectively. These results indicate that the amorphous phase does not have great changes during deep cryogenic cycling treatment (DCT), such as crystallization
By using the data shown above with Eqs. (2) and (3), x of As-cast and DCT30 are calculated to be 1.30% and 2.06%, respectively, which suggests that more free volume has been induced for lower casting temperature (LT) samples upon DCT and the BMGs are rejuvenated. It agrees well with the results from thermal analysis. These results suggest that unlike High casting temperature (HT) samples, LT samples can be rejuvenated upon DCT
Summary
The bulk metallic glasses (BMGs) have attracted a lot of interests because of their superior mechanical properties such as high fracture strength and large elastic limit, which originates from their unique long-range disordered microstructures [1–3]. To suppress the nucleation and growth of crystalline phase during solidification, rapid quenching techniques are always required during the fabrication of BMGs [4–6]. The non-equilibrium solidification process makes BMGs possess higher configurational potential energy compared with their crystalline counterparts [7]. During annealing, the microstructures of BMGs tend to change toward a lower energy state (relaxation), which makes them more like the crystalline counterparts [8]. The so-called relaxation process of BMGs always degrades the properties of them, especially the mechanical properties, e.g., the embrittlement of BMGs after relaxation [9]. The microstructures and mechanical properties of each sample are investigated in detail
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
