Fluxing of Pd-Si-Cu bulk metallic glass and the role of cooling rate and purification
Fluxing of Pd-Si-Cu bulk metallic glass and the role of cooling rate and purification
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DOI：
10.1016/j.actamat.2014.03.008
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发表时间：
2014-06
期刊：
影响因子：
9.4
通讯作者：
Davide Granata;E. Fischer;V. Wessels;J. F. Löffler
中科院分区：
文献类型：
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作者：
Davide Granata;E. Fischer;V. Wessels;J. F. Löffler
氧化硼助熔是一种同时改善大块金属玻璃（BMG）许多性能的有趣的加工技术。这涉及玻璃形成能力（即大于三倍的临界铸造厚度），以及热特性和机械特性的显著改善。特别是，更好地了解焊剂处理可以进一步提高韧性和延展性，这是结构应用所必需的。本文研究了助熔对Pd-Si-Cu非晶合金的影响。通过研究四种不同加工的材料（即铸造、水淬、熔剂铸造和熔剂合金），可以将所施加的冷却速率和与熔剂处理相关的净化的影响解耦。更好的玻璃形成能力与非均匀性的减少有关，而热特性取决于这两个参数。较慢的淬火速率和抑制异质形核的相互作用反映在扩展的过冷液体范围内，提高了BMG的成形性。还获得了更好的延展性，并且可以用纯化来解释，这与氧浓度的降低有关。总之，助熔试样的性能不仅通过减少非均匀成核来改善，而且还通过改变助熔过程中的冷却速率来改善。这项研究说明了充分处理BMG形成液体以实现改进的性能和铸件厚度的重要性。
Boron oxide fluxing represents an interesting processing technique for attaining a simultaneous improvement in many properties of bulk metallic glasses (BMGs). This concerns glass-forming ability (i.e. a more than three times larger critical casting thickness), in combination with a significant improvement of thermal and mechanical characteristics. In particular, a better understanding of the flux treatment can result in further enhancement of toughness and ductility, which is crucially needed for structural applications. This study investigates the effects of fluxing of Pd–Si–Cu BMGs. By studying four differently processed materials (i.e. cast, water-quenched, fluxed-cast and fluxed alloys), the influences of applied cooling rate and purification associated with flux treatment can be decoupled. The better glass-forming ability is linked to the reduction of heterogeneities, whereas the thermal characteristics depend on both parameters. The interplay of slower quenching rates and the suppression of heterogeneous nucleation is reflected in an extended supercooled liquid range, improving the formability of the BMG. Better ductility is also obtained and can be explained in terms of purification, which is correlated with a decrease in oxygen concentration. In summary, the properties of fluxed specimens are improved not only by the reduction of heterogeneous nucleation, but also via modified cooling rates during fluxing. This study illustrates the importance of adequate processing of BMG-forming liquids to achieve improved properties and casting thicknesses.