超快扫描量热揭示铝基金属玻璃过冷液态:接近液体脆度的理论极限（英文）

铝基非晶合金具有密度低、强度高、耐腐蚀等诸多优异性能;然而,铝基非晶合金形成能力差,一般需要非常高的冷却速率,这限制了铝基非晶合金的应用.玻璃形成理论认为形成能力与过冷液体密切相关.但在一般升温测量时,铝基非晶合金不显示玻璃转变或过冷液体,而是直接变成晶态.目前为止,关于铝基非晶合金的玻璃转变和过冷液体属性仍然是未知的.本文采用超快速差热分析方法(Flash DSC)使得升温速度达到10000 K s^-1,测量了20余种常见铝基非晶合金的玻璃转变行为和过冷液体特征.发现铝基非晶合金普遍具有很高的液体脆度系数(m),其中某些成分m>160,已经接近理论上预测的脆度系数上限m^175.通过系统研究这些成分的形成能力,发现铝基非晶合金的玻璃形成能力与脆度系数成反相关,而且这种相关不是线性的.只有m<100时,降低m才会对玻璃形成能力有明显影响;相反, m>100的玻璃形成力普遍较弱,而且随m变化不显著.因此,过高的液体脆度系数可能是铝基非晶合金形成能力差的一个重要原因.

Revealing hidden supercooled liquid states in Al-based metallic glasses by ultrafast scanning calorimetry: Approaching theoretical ceiling of liquid fragility

Metallic glasses(MGs)are amorphous alloys with a number of unique properties that are attractive for the fundamental understanding of the nature and applica-tions of disordered systems1–17].Generally,MGs might be grouped into two categories based on their glass forming ability(i.e.,the ease of glass formation by cooling a liquid):in one case,large or bulk volumes may be slowly cooled to the glassy state from the melt.This category is usually called as bulk metallic glass formers18–22].In contrast,certain MGs,represented by aluminum(Al)-23,24]and some iron(Fe)-25,26]based MGs,can be synthesized mainly by rapid solidification processes such as melt spinning or vapor deposition.These MGs are often denoted as marginal MG-formers23–25].