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金属玻璃：惰性or活泼？
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金属玻璃由于其特殊的成分及原子结构，在外界条件下往往体现出比较惰的性质。比如受力难屈服（高强度、高弹性），受到摩擦时损耗更小（高硬度、耐磨），在酸盐等条件下耐腐蚀能力强，电阻随温度变化很小，等等。
COMMENTS:
One of bottlenecks of metallic glasses is applications. This paper presents interesting results using unique properties (outstanding efficiency of Fe-based metallic glass powders in degrading organic water contaminants) of metallic glass for the application. The authors have demonstrated and compared that the metallic glass has better chemical performance than the commercial one. They show that metastable thermodynamic nature and the particle surface topography are the major factors controlling the chemical performance of the metallic glass. Their findings may open a new opportunity for functional applications of metallic glasses. The paper is well written and the results are very interesting not only in metallic glass filed. I think the paper fit well of the requirements of Adv. Func. Mater. I then recommend the publications.
https://blog.sciencenet.cn/blog-202254-574362.html
上一篇：何谓“金属玻璃”？
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可是在某些条件下它们可以表现出更活泼的性质。比如加热时更低温度就可以转化为液态（玻璃转变现象，Tg：0.5~0.6Tm），某些铁基金属玻璃在非常低的磁场下磁化（软磁性能优异），受力容易弹性变形（弹性模量低），等等。
最近，我们发现在处理污水中的偶氮染料时，金属玻璃表现出非常高的活性，见图一。比如球磨后的铁基金属玻璃粉比晶态铁粉的活性约高200倍，而且热激活能也要低一些，这应该和金属玻璃的亚稳态结构有密切的关系【文章见Adv.Funt.Mater.2012,DOI: 10.1002/adfm.201103015】。而且我们最新的结果表明Mg-Zn基金属玻璃粉在降解偶氮染料时活性更高，达到晶态铁粉的1000倍以上【文章见Scientific Reports 2,418(2012).】。
那为什么金属玻璃会表现出既惰性又活泼的性质呢？或者说金属玻璃什么情况下惰，什么情况下活泼呢？
先来说说为什么惰。金属玻璃内的原子虽然无序排列，但是浑然一体，缺少晶体中的晶界、位错等缺陷薄弱点，见图二。因此凡是和晶界位错有关的现象，金属玻璃都不会体现出来，也就是体现出惰性，比如晶界腐蚀，晶界位错滑移导致的屈服塑性变形等。
那为什么活泼呢？这要从势能地形图说起，见图三。一般认为玻璃态是亚稳态，处于某能量极小值但非最小值（对应晶态），因此无论从经典力学的能量角度考虑还是量子力学角度考虑，和晶态比，玻璃更容易被激活。因此表现出低模量、低固-液转变温度（玻璃转变）等。因此可以这样简单理解为涉及整体热力学统计性质的现象金属玻璃会表现出高活性。
惰？！活泼？！——这就是金属玻璃，充满了矛盾。因为有阴又有阳，变幻使之变得美丽而有魅力！
附上第一篇文章在AdFM的审稿意见：
IMPORTANCE:
1. Critically important (top 5%)
DATA OBTAINED VERIFY HYPOTHESIS AND CONCLUSIONS:
Yes
APPROPRIATE LENGTH:
Yes
OTHER JOURNAL:
RECOMMEND ACCEPTANCE:
COMMENTS:
One of bottlenecks of metallic glasses is applications. This paper presents interesting results using unique properties (outstanding efficiency of Fe-based metallic glass powders in degrading organic water contaminants) of metallic glass for the application. The authors have demonstrated and compared that the metallic glass has better chemical performance than the commercial one. They show that metastable thermodynamic nature and the particle surface topography are the major factors controlling the chemical performance of the metallic glass. Their findings may open a new opportunity for functional applications of metallic glasses. The paper is well written and the results are very interesting not only in metallic glass filed. I think the paper fit well of the requirements of Adv. Func. Mater. I then recommend the publications.
https://blog.sciencenet.cn/blog-202254-574362.html
上一篇：何谓“金属玻璃”？
下一篇：五重对称：自然界美的溺爱！
