Experimental and numerical engineering of novel eutectic high melting Mo-Si-Ti alloys processed by additive manufacturing: microstructure, texture and ensuing properties

通过增材制造加工的新型共晶高熔点 Mo-Si-Ti 合金的实验和数值工程：微观结构、织构和后续性能

• 批准号: 424801257
• 负责人: Professor Dr.-Ing. Martin Heilmaier
• 金额: --
• 依托单位: Institut für Angewandte Materialien - Werkstoffkunde (IAM-WK)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/424801257?language=en
• 关键词: Experimental; numerical; engineering; novel; eutectic

The proposed study aims at a combined experimental and modeling engineering approach for developing novel eutectic alloys within the Molybdenum-Silicon-Titanium system. Multi-phase refractory metal (RM) silicide alloys are considered to be very promising candidates for ultrahigh temperature structural applications beyond currently used Ni-base superalloys. However, because of their rather (i) high melting point and (ii) brittle-to-ductile transition temperature they are difficult to process in complex shaped parts using conventional equipment. Therefore, a still novel bottom-up processing method called additive manufacturing (AM) is applied aiming at understanding the elementary mechanisms for this far from equilibrium process governing microstructural development utilizing texture formation and phase field modeling. Additionally, these alloys usually suffer from a mid-temperature phenomenon called “pesting”, the spontaneous sublimation of RM-based oxides. Specifically, employing selected electron beam melting (SEBM) allows the production of parts in a protective (high vacuum) environment at elevated powder bed temperatures which makes SEBM the best choice for manufacturing of “clean” and crack-free samples of oxidation-sensitive alloy systems. In own preliminary work we could demonstrate that even conventionally processed, i.e. arc-melted, fully eutectic Mo27-Si20-Ti53 (composition given in at.%) possesses attractive creep properties and simultaneously does not show “pesting”, in other words it reveals already satisfying oxidation resistance. It was concluded that both these properties benefit from the rather fine and lamellar microstructure. Since AM is known to be a manufacturing process exhibiting high cooling rates and thermal gradients, we anticipate even finer and likely far from equilibrium microstructures on the one hand and crystallographic texture formation on the other. The properties of such microstructures are hitherto unknown and will be explained based on elementary physical metallurgy mechanism. Thus, this proposal reflects a combined effort by colleagues with mutually supplementing competences in the fields of AM of high temperature structural materials, texture formation and phase field simulation.

该研究旨在结合实验和建模工程方法，在钼-硅-钛系统中开发新型共晶合金。多相难熔金属（RM）硅化物合金被认为是非常有前途的候选人，用于低温结构应用目前使用的镍基高温合金之外。然而，由于它们相当高的（i）熔点和（ii）脆韧转变温度，它们难以使用常规设备加工成复杂形状的部件。因此，仍然是一种新的自下而上的加工方法，称为增材制造（AM）的应用，旨在了解这个远离平衡过程的基本机制，利用纹理形成和相场建模的微观结构的发展。此外，这些合金通常遭受称为“粘结”的中温现象，即RM基氧化物的自发升华。具体而言，采用选择性电子束熔化（SEBM）允许在保护性（高真空）环境中在升高的粉末床温度下生产部件，这使得SEBM成为制造氧化敏感合金系统的“清洁”和无裂纹样品的最佳选择。在自己的初步工作中，我们可以证明，即使是常规加工的，即电弧熔化的，完全共晶的Mo 27-Si 20-Ti 53（成分以at.%给出），具有有吸引力的蠕变性能，同时不显示“蠕变”，换句话说，它显示出已经令人满意的抗氧化性。得出的结论是，这两个性能受益于相当细的和层状的显微组织。由于AM已知是一种表现出高冷却速率和热梯度的制造工艺，因此我们一方面预期甚至更精细且可能远离平衡的微观结构，另一方面预期晶体学织构形成。这种微结构的性质迄今为止尚不清楚，将根据基本物理冶金机理来解释。因此，该提案反映了同事们在高温结构材料AM，织构形成和相场模拟领域相互补充能力的共同努力。