中文摘要：

非晶合金是熔体深度过冷至玻璃态转变,结构发生突然＂冻结＂而形成的玻璃态固体.在远低于玻璃转变温度,非晶合金的宏观断裂通常由塑性变形局部化剪切带诱导.尽管非晶塑性机理还未完全揭示,但普遍认为剪切带模式的裂尖塑性流动源于材料内部原子集团的局部剪切重排,即＂剪切转变区（shear transformation zone,STZ）＂事件.但是,越来越多的工作表明,非晶合金的断裂并非总是由剪切带诱导,而呈现脆性的拉伸正断,并涌现出一种新的断裂面斑图：纳米周期条痕.针对这一全新的断裂能耗散过程,我们在2008年提出了非晶合金的＂拉伸转变区（tension transformation zone,TTZ）＂模型.本文将简要介绍非晶合金＂拉伸转变区＂模型的提出、内涵本质、激活条件、原子模拟和韧脆转变实验验证等,并对该模型的未来发展进行评述.

英文摘要：

An amorphous alloy is a glassy solid that is formed through the supercooling of a melt. As the melt cools via the glass transition, its atoms freeze into a long-range disordered structure. Amorphous alloys represent a relatively young class of materials, having been first reported in 1960 when Duwez and co-workers produced Au-Si alloys by developing the rapid-quenching technology. The advent of amorphous alloys, especially the bulk samples with their characteristic size in excess of 1 mm, has aroused much interests in the basic science of glass transition, glass structure, and their intriguing properties. For crystalline metals, their structure can be well described by the period lattices and lattice defects including dislocations, twins, stacking faults, grain doundaries, etc. However, these traditional structural defects are not defined in amorphous alloys. Therefore, this type of atomic-disordered alloys manifest a series of excellent mechanical properties, including extraordinary strength, high hardness, large elastic limit and relatively high fracture toughness, making them attractive candidates for many potential applications as structural materials. At temperatures far below the glass transition temperature, the failure of amorphous alloys is generally induced by 10 nm thick shear banding with the single-dominated or multiple mode. It is well known that the shear banding is an instability mode of plastic flow from homogeneous to localized feature. Although the precise mechanism for amorphous plasticity is not well discovered, it is widely accepted that the shear-banding-mediated plasticity originates from a cascade of inelastic shear rearrangements of local atomic groups, called shear transformation zones（STZs）. The STZs are thermally activated events with the transient nature, driven by shear stress and giving rise spatially to Eshelby fields. However, many recent works have shown that the failure of amorphous alloys is not always dominated by the shear banding; instead, a brittle failure will take pl