Systematic investigation of abnormal grain growth induced by a cyclic heat treatment in Fe-Mn-Al-Ni-X (X = Cr, Ti) shape memory alloys

Fe-Mn-Al-Ni-X (X = Cr, Ti) 形状记忆合金循环热处理引起的异常晶粒生长的系统研究

• 批准号: 400008732
• 负责人: Professor Dr.-Ing. Thomas Niendorf
• 金额: --
• 依托单位: Fachgebiet Metallische Werkstoffe
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/400008732?language=en
• 关键词: Systematic; investigation; abnormal; grain; growth

Availability of new, cost-efficient alternatives to widely used Nitinol (Ni-Ti) shape memory alloy (SMA) is crucial for establishing new applications and markets for SMAs. Cost-intensive processing combined with the relatively high material costs for Ni-Ti are major roadblocks, particularly for applications demanding high material quantities, e.g. damping elements for constructions. Iron-based shape memory alloys are promising candidates to overcome these issues. Processing routes from steel industry can be used and material costs are relatively low. In particular, the newly developed Fe-Ni-Co-Al-X (X = Ta, Nb, Ti) and Fe-Mn-Al-Ni-X (X = Ti, Cr) SMAs are high potential candidates as they show SMA performance similar to Ni-Ti in terms of transformation stresses and strains.One of the challenges towards industrial application of both alloys is the establishment of suitable microstructures with respect to phase fractions, grain size, grain morphology and grain orientation. In particular, the pseudoelastic behavior in Fe-Mn-Al-Ni-X strongly depends on the relative grain size. The grain size has to exceed the cross section of the sample to promote good pseudoelasticity, i.e. an oligocrystalline microstructure has to be present. A new method to establish oligocrystalline microstructures is abnormal grain growth (AGG) induced by a cyclic heat treatment.Advantages of the cyclic heat treatment compared to well-known methods promoting secondary recrystallization include dimensional stability during processing and the repeatability over several heat treatment cycles. Although single important factors such as size of substructures formed in the course of treatment have already been identified, a deep understanding of the elementary mechanisms and their interplay as well as critical evaluation of influencing factors are still lacking in open literature. Moreover, a strong impact of the chemical composition on AGG was observed in our preliminary studies on Fe-Mn-Al-Ni-X.The research project applied for aims at a deep understanding of AGG induced by cyclic heat treatment in Fe-Mn-Al-Ni-X. Critical influencing parameters of the process will be varied and evolving microstructures characterized. Afterwards, their impact on AGG will be evaluated and thereby key parameters identified. A further important aspect is investigation of the effect of small amounts of Chromium and Titanium on AGG as compared to the quaternary alloy. Finally, findings will be implemented in a model describing grain growth kinetics in the course of cyclic heat treatment and AGG, respectively.

获得广泛使用的镍钛形状记忆合金(SMA)的新的、低成本的替代品对于为SMA建立新的应用和市场至关重要。成本密集的加工和相对较高的材料成本是镍钛合金的主要障碍，特别是对于要求高材料数量的应用，例如建筑用减震元件。铁基形状记忆合金是很有希望克服这些问题的候选材料。可以采用钢铁行业的加工路线，材料成本相对较低。特别是，新开发的Fe-Ni-Co-Al-X(X=Ta，Nb，Ti)和Fe-Mn-Al-Ni-X(X=Ti，Cr)形状记忆合金是很有潜力的候选者，因为它们在相变应力和应变方面表现出与Ni-Ti相似的形状记忆合金性能。这两种合金工业应用的挑战之一是建立关于相组成、晶粒度、晶型和晶向的合适的微观结构。特别是，Fe-Mn-Al-Ni-X的伪弹性行为强烈地依赖于相对晶粒度。晶粒尺寸必须超过样品的横截面，以促进良好的伪弹性，即必须存在少晶组织。一种新的建立低晶组织的方法是循环热处理引起的异常晶粒长大(AGG)。与众所周知的促进二次再结晶的方法相比，循环热处理的优点包括加工过程中的尺寸稳定性和多次热处理循环的可重复性。虽然已经确定了治疗过程中形成的单个重要因素，如亚结构的大小，但对其基本机制及其相互作用的深入了解以及对影响因素的批判性评估仍缺乏公开文献。此外，在对Fe-Mn-Al-Ni-X合金的初步研究中，观察到化学成分对AgG有很大的影响。本研究项目旨在加深对Fe-Mn-Al-Ni-X合金循环热处理诱发AgG的理解。这一过程的关键影响参数将是不同的，并将表征不断演变的微观结构。之后，将评估它们对AGG的影响，从而确定关键参数。另一个重要的方面是研究与四元合金相比，微量铬和钛对AgG的影响。最后，研究结果将在一个模型中实现，该模型分别描述了循环热处理和AGG过程中的晶粒生长动力学。

项目成果

Functionally graded structures realized based on Fe–Mn–Al–Ni shape memory alloys

• DOI: 10.1016/j.scriptamat.2020.10.057
• 发表时间: 2021-03
• 期刊: Scripta Materialia
• 影响因子: 6
• 作者: M. Vollmer;A. Bauer;M. Kriegel;M. Motylenko;T. Niendorf

Induction Butt Welding Followed by Abnormal Grain Growth: A Promising Route for Joining of Fe–Mn–Al–Ni Tubes

• DOI: 10.1007/s40830-019-00261-2
• 发表时间: 2020-01
• 期刊: Shape Memory and Superelasticity
• 影响因子: 2.2
• 作者: M. Vollmer;D. Baunack;D. Janoschka;T. Niendorf

Promoting abnormal grain growth in Fe-based shape memory alloys through compositional adjustments

• DOI: 10.1038/s41467-019-10308-8
• 发表时间: 2019-05
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: M. Vollmer;T. Arold;M. Kriegel;V. Klemm;S. Degener;J. Freudenberger;T. Niendorf