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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.
Amorphous alloys are glassy solids formed by the subcooling of the melt to the glassy state, with a sudden “freezing” of the structure, and macroscopic rupture of the amorphous alloy, usually much below the glass transition temperature, is usually localized by plastic deformation Although the amorphous plasticity mechanism has not yet been fully revealed, it is generally accepted that the shear-tip plastic flow in the shear band mode originates from the local shear rearrangement of the atomic groups within the material, namely the “shear transformation zone However, more and more work shows that the fracture of amorphous alloy is not always induced by the shear band, but presents a brittle tensile normal fault and a new fracture surface spot emerges In view of this new process of energy dissipation in fracture, we proposed a ”tension transformation zone (TTZ)“ model of amorphous alloy in 2008. This article will briefly introduce the non- Crystal alloy ”tensile transition zone " model proposed, the nature of the connotation, activation conditions, atomic simulation and ductile-brittle transition experiment verification, etc., and the future development of the model are reviewed.