金属玻璃的自然老化

Natural aging of metallic glasses

金属玻璃本质上是亚稳态的,在高温下倾向于通过弛豫和晶化达到低能状态.然而在室温下,通常认为其无定形结构可以保持足够长的时间.本文报道了在自然环境中保存12年的一系列CuZr金属玻璃的长期稳定性.结果表明,低Zr含量的CuZr金属玻璃(低于66.7 at%)由于室温氧化引起了严重的失稳;高Zr含量的CuZr金属玻璃形成了一层致密的ZrO_(2)而保留了光泽的表面,尽管如此,其热性能(如玻璃转变温度T_(g)和晶化温度T_(x))由于氧的渗透发生了明显改变.本文的研究结果不仅为理解金属玻璃的热稳定性提供了重要的见解,而且对无序固体的工程应用具有重要意义.

Metallic glasses(MGs)are intrinsically metastable,and tend to relax and crystallize at elevated temperatures.However,it is generally believed that their amorphous nature at room temperature can be retained for a sufficiently long time.Herein,we report the long-term stability of a series of Cu-Zr MGs in natural environment after twelve years.Surprisingly,the Cu-Zr MGs with a low Zr content(i.e.,below 66.7 at%)encountered severe instability,which was induced by room-temperature oxidation.Although those with a high Zr content preserve the shiny surfaces due to the formation of a dense ZrO_(2)layer,their thermal properties(e.g.,glass transition temperature T_(g)and onset crystallization temperature T_(x))are appreciably changed due to oxygen permeation.Our findings not only shed light on the understanding of the thermal stability of MGs in general,but also have important implications for engineering applications of these disordered solids.