Bulk Metallic Glasses
Bulk Metallic Glasses
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DOI：
10.4028/www.scientific.net/msf.604-605.229
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发表时间：
2008-10
期刊：
影响因子：
--
通讯作者：
C. Byrne;M. Eldrup
中科院分区：
文献类型：
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作者：
C. Byrne;M. Eldrup
快速淬火技术长期以来一直成功地应用于带状金属玻璃的制备。直到最近几年，研究活动才转向大块金属玻璃（BMG）的合成，其形式是几毫米厚的铸锭。这些材料只能通过铸造技术获得特定合金成分，其特点是具有特别高的玻璃化倾向。大块非晶合金具有低弹性模量和高屈服应力的特点。通常的想法是，非晶合金经历工作软化，变形集中在剪切带，这可能受到几何约束，导致硬度和耐磨性大幅增加。通过结晶可以进一步提高机械性能。事实上，剪切带的运动可以通过在材料中加入第二相来对比，第二相可以通过控制结晶直接产生。在铁基体系中已经获得了软磁性能，它们与微观结构的微小变化密切相关，从完全非晶相到不同晶粒尺寸的纳米晶相。大块金属玻璃的高热稳定性使得在玻璃化转变和结晶之间的温度范围内进行压缩和成型过程成为可能。本文的目的是介绍不同成分的大块金属玻璃的形成和性能的最新研究结果。以Zr， Fe， Mg和pd基材料为例，重点介绍机械和磁性能。
Rapid quenching techniques have been successfully applied since long time for the preparation of metallic glasses in ribbon form. Only in the recent years, the research activity addressed towards the synthesis of bulk metallic glasses (BMG), in form of ingots with a few millimetres in thickness. These materials can be obtained by casting techniques only for selected alloy compositions, characterised by a particularly high glass-forming tendency. Bulk amorphous alloys are characterised by a low modulus of elasticity and high yielding stress. The usual idea is that amorphous alloys undergo work softening and that deformation is concentrated in shear bands, which might be subjected to geometrical constraints, resulting in a substantial increase in hardness and wear resistance. The mechanical properties can be further improved by crystallisation. In fact, shear bands movement can be contrasted by incorporating a second phase in the material, which may be produced directly by controlled crystallisation. Soft magnetic properties have been obtained in Fe-based systems and they are strongly related to small variations in the microstructure, ranging from a fully amorphous phase to nanocrystalline phases with different crystal size. The high thermal stability of bulk metallic glasses makes possible the compression and shaping processes in the temperature range between glass transition and crystallisation. Aim of this paper is to present recent results on glass formation and properties of bulk metallic glasses with various compositions. Examples will be reported on Zr, Fe, Mg and Pd-based materials, focussing on mechanical and magnetic properties.