高氧含量锆基非晶合金非晶形成能力的提高机理及力学性能的研究

Since the discovery of Zr-based metallic glasses, oxygen has been considered to be destructive to the glass forming ability and mechanical properties. This problem has not yet been solved and hinders the wide application of Zr-based metallic glasses. This project proposes to investigate the competing phases in multi-component alloy system with high oxygen content, and to improve the glass forming ability by adjusting the alloy composition. Meanwhile, through the analysis of the oxygen distribution in the alloy, this project also elucidates the mechanism of the ignition and propagation of shear bands. Eventually, Weibull analysis is employed to quantify the transition process of deformation mechanism changing from plasticity to brittleness of the Zr-based metallic glass by studying the statistical dispersion in compression strength under varied oxygen levels. This project focuses on both fundamental research and industrial demand, and provides a guidance to solve the glass forming ability and brittleness problem of Zr-based metallic glasses with high oxygen content.

自锆基非晶发现以来，氧元素就被认为对其非晶形成能力及力学性能有破坏作用，这一问题至今仍未解决，并阻碍着锆基非晶合金的大范围应用。本项目提出通过对高氧含量下多元合金体系中竞争相的分析，应用合金成分的优化及调整来解决高氧含量造成非晶形成能力下降的问题；并研究氧元素在合金中的分布，探索氧元素对于Zr基非晶合金剪切带的产生及发展的作用机理，应用Weibull方法统计研究其强度的变化，量化氧含量的变化对其塑性的影响以及塑/脆性转变的过程。本项目将基础研究与工业需求相结合，通过本项目的研究，将为解决高氧状态中Zr基非晶合金非晶形成能力差、脆性较高的问题提供理论依据。

本项目通过在锆基非晶合金中系统的添加氧元素，研究氧元素对其非晶形成能力及力学性能的影响及其内在机理。通过本项目的研究，获得以下有意义的结果：（1）实现了具有不同氧含量的Zr50.75(Cu90Ni10)40.25Al9非晶合金的可控制备；氧元素的添加诱使了体系中τ3相的析出，使得其非晶形成能力随氧含量的升高逐渐下降；并且氧元素富集在τ3相中。（2）通过对具有不同氧含量的Zr61Cu25Al12Ti2非晶合金的压缩强度及塑性的研究发现，当氧含量小于3500at.ppm时，非晶合金的塑性变形能力得以保持，进一步添加氧元素则会导致非晶合金的塑性变形行为由多重剪切带主导转变为单一剪切带所主导，从而降低了其塑性变形能力。（3）氧元素的添加使得非晶合金的剪切转变区尺寸减小，抑制了多重剪切带的生成，从而降低了其塑性。（4）氧元素的添加促使了锆基非晶合金中有序相的形成：当氧含量在3500at.ppm以下时，非晶合金中缺位有序结构含量在14%左右，且并未发现其具有中程有序结构。而在氧含量高于3500at.ppm时，非晶合金中出现了中程有序结构，且随着氧含量的升高非晶合金中缺位有序结构和中程有序结构含量均大幅度提高。这说明氧元素的添加改变了非晶合金的微观结构，从而影响了其宏观力学性能。