Heat-treatable Chromium-based alloys for extrem temperatures

适用于极端温度的可热处理铬基合金

• 批准号: 287397384
• 负责人: Privatdozent Dr.-Ing. Mathias Galetz
• 金额: --
• 依托单位: Lehrstuhl Metallische Werkstoffe
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/287397384?language=en
• 关键词: Heat; treatable; Chromium; based; alloys

This study aims to develop new heat treatable Cr-Si-Ge alloys with Cr > 90 at%, which show complete solubility at high temperatures. The heat treatment cycle allows control of the microstructure. The desired microstructure consists of a Cr solid solution matrix and intermetallic A15-phase precipitates. The precipitation behaviour and A15/Matrix interface as well as mechanical and physical properties (especially creep and oxidation resistance) will be investigated with regard to microstructure. The heat treatment parameters will be optimized in order to obtain a high A15/matrix phase ratio and enhanced properties. In the second step, the alloying potential of the Cr-Si-Ge system will be evaluated using two main approaches. First is the addition of a substitutional alloying element (in both A15 and Cr) which provides solid solution strengthening as well as substituting chromium in the A15 phase. Molybdenum shows a high alloying potential with pure chromium as well as in the A15-Cr3Si phase. Mo-alloyed chromium (with up to 9 at% Mo) shows complete solubility in all temperature ranges up to the melting point. Alloying with up to 0.2 at% Mo improves the creep resistance of pure chromium to an order of magnitude and increases the room temperature ductility. In addition, it is shown that alloying Cr3Si with Mo (up to 30 at.%) enhances the oxidation resistance in a broad temperature range by improved protection through SiO2 formation. Also, concerning the oxidation resistance, Mo is interesting because in comparison to Cr, Mo shows oxide pesting during oxidation which can locally increase the Si or Ge activity. This is to be investigated. The second approach is the addition of an element that forms the A15 phase, which can also substitute Si and Cr, and shows a high temperature dependent solubility in chromium solid solution. The Cr-Pt system shows an analogous binary composition as the Cr-Si and Cr-Ge systems composed of a solid solution and an A15-Cr3Pt phase field. The system provides the required steep solvus line in the Cr-rich region. It is aimed to study how soluble to A15 precipitates are and how their volume fraction can be increased and eventually stabilized through the addition of platinum. Therefore, it is necessary to study the interface properties between the A15 precipitates and the solid solution matrix. Potential applications of this system are directly as an optimized alloy or as a metal matrix, which might be further enhanced via oxide dispersed strengthening and used for turbine applications as well as applications in the chemical industry, where extrem corrosion resistance is required at elevated temperatures.

本研究旨在开发新的可热处理的Cr-Si-Ge合金，Cr > 90 at%，在高温下显示出完全溶解性。热处理循环允许控制微观结构。所需的显微组织由Cr固溶体基质和金属间A15相沉淀物组成。从微观结构方面研究了A15合金的析出行为、A15/基体界面以及力学和物理性能（特别是抗蠕变和抗氧化性能）。热处理参数将被优化，以获得高的A15/基体相比例和增强的性能。在第二步中，将使用两种主要方法评估Cr-Si-Ge系统的合金化潜力。首先是添加替代合金元素（在A15和Cr两者中），其提供固溶体强化以及替代A15相中的铬。钼与纯铬以及在A15-Cr 3Si相中显示出高合金化潜力。钼合金铬（含最高达9原子%的钼）在熔点以下的所有温度范围内都显示出完全的溶解性。与高达0.2at%的Mo合金化将纯铬的抗蠕变性提高了一个数量级，并增加了室温延展性。此外，它表明，合金化Cr 3Si与Mo（高达30原子%），通过SiO2形成的改善保护，在宽温度范围内增强抗氧化性。此外，关于抗氧化性，Mo是令人感兴趣的，因为与Cr相比，Mo在氧化期间显示氧化物穿孔，这可以局部地增加Si或Ge活性。这是要调查的。第二种方法是添加形成A15相的元素，其也可以取代Si和Cr，并且在铬固溶体中显示出高的温度依赖性溶解度。Cr-Pt系统显示出与Cr-Si和Cr-Ge系统类似的二元组成，其由固溶体和A15-Cr 3 Pt相场组成。该系统在富铬区域提供了所需的陡峭固溶线。其目的是研究如何可溶于A15沉淀物，以及如何通过添加铂来增加并最终稳定它们的体积分数。因此，有必要研究A15析出相与固溶体基体之间的界面性质。该系统的潜在应用是直接作为优化的合金或作为金属基体，其可通过氧化物分散强化进一步增强，并用于涡轮机应用以及化学工业中的应用，其中在高温下需要极端耐腐蚀性。