Microstructure Evolution of EBM Gamma Titanium Alumiide (TNM-B1)

EBM 伽马钛铝化物（TNM-B1）的微观结构演变

• 批准号: 406109547
• 负责人: Professor Dr.-Ing. Christoph Leyens
• 金额: --
• 依托单位: Institut für Werkstoffwissenschaft
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/406109547?language=en
• 关键词: Microstructure; Evolution; EBM; Gamma; Titanium

Over the past decade additive manufacturing has become of great scientific and industrial interest. This enables tailored component manufacturing for a wide range of applications, for example in aerospace and medicine industry. These industries often rely on difficult to process materials. Powder-bed based methods like the electron beam melting process (EBM) emerged as an excellent choice for such use cases due to high process temperatures and slow cooling rates.Titan aluminides are known to be a potential candidate for material substitution in aerospace industry due to their excellent high temperature behavior as well as low density. However these materials exhibit a ductile-to-brittle transition at around 700 °C. Thus casting or processing by selective laser melting (SLM), a generative process as well, are susceptible to thermal induced cracks. The EBM process could establish as an alternative processing route for near net shape manufacturing of complex parts consisting of those materials.This project focusses on the experimental investigation of the microstructural evolution of EBM-manufactured TNM-B1 parts – a further development of TNM-alloy – along a common EBM manufacturing chain. TNM alloys are titanium aluminides with improved workability due to decreased segregation and texture susceptibility compared to conventional gamma-TiAl alloys. The microstructure of TNM-alloys significantly influences the component properties and is controlled by a thermal treatment subsequent to the EBM-processing. Thus a key point of this project is to investigate the influence of those two processes on the microstructural evolution of TNM alloys. Thereby two main aspects shall be addressed. First a possible evaporation of elements which lead to changes of the chemical and phase composition and second a possible microstructural change in comparison to casted TNM-B1 components. Former researches already highlighted the evaporation of aluminum during EBM-processing for other titanium aluminides. For the TNM system this could lead to an increased amount of brittle alpha2-TiAl-phase and thus influence microstructure and residual stress state. An increased risk of thermal induced cracking especially during quenching steps (e.g. subsequent to the solution annealing heat treatment) might be the consequence. Taking this into account the evolution as well as the stability of residual stresses along the EBM-manufacturing chain shall be investigated. The emphasis of the residual stress examinations will be on the multi-step heat treatment subsequent to the EBM-process.Based on all results the applicability of the EBM-process for component manufacturing from TNM-B1 or TNM-alloys will be evaluated. There the outcomes of the microstructural and residual stress state investigations will also be used to identify relevant and critical processes and process parameters along the EBM manufacturing chain.

在过去的十年中，上瘾的制造业已成为极大的科学和工业兴趣。这使得为​​广泛应用（例如航空航天和医学行业）提供了量身定制的组件制造。这些行业通常依靠难以处理材料。基于粉末状的方法，例如电子束熔化过程（EBM），由于高过程温度和缓慢的冷却速率而成为此类用例的绝佳选择。由于其出色的高温行为和低密度以及低密度，因此已知Titan铝制是航空航天工业材料替代的潜在候选者。但是，这些材料在700°C左右显示出延性到脆性的过渡。选择性激光熔化（SLM）的铸造或处理也很容易受到热感应裂纹的影响。 EBM工艺可以作为由这些材料组成的复杂零件的接近净形制造的替代处理途径。该项目重点介绍了EBM制造的TNM-B1零件的微观结构演化的实验投资 - TNM合金的进一步开发 - 沿着共同的EBM制造链。 TNM合金是钛合金，由于与常规伽马 - 脉冲合金相比，由于隔离和质地敏感性的提高，可工行提高了可加工性。 TNM合金的微观结构显着影响组件特性，并受到EBM处理后的热处理控制。该项目的一个关键是研究这两个过程对TNM合金微结构演化的影响。因此应解决两个主要方面。首先，与铸造TNM-B1成分相比，可能导致化学和相位组成变化的元素经济，其次可能是可能的微结构变化。以前的研究已经强调了在其他钛合金的EBM加工过程中铝的蒸发。对于TNM系统，这可能会导致脆性α2-二极管的量增加，从而影响微观结构和残留应力状态。导致热引起的裂纹的风险增加，尤其是在淬火步骤（例如，在溶液退火处理后）的风险可能是结果。考虑到这一点，应研究沿EBM制造链的残余应力的演变以及稳定性。残留应力检查的重点将放在EBM过程之后的多步热处理上。基于所有结果，将评估EBM过程中EBM过程中的适用性，将评估由TNM-B1或TNM合金制造的组件制造。微观结构和残余压力状态投资的结果也将用于确定沿EBM制造链沿线的相关和关键过程以及过程参数。