SBIR Phase I: Highly Processable High Performance Ni Superalloys for Heat Exchanger Applications

这个小型企业创新研究第一阶段项目将设计和开发一种用于高温换热器应用的新型高性能镍高温合金材料。合金设计将利用Questek在镍高温合金建模、设计和原型方面的现有努力，包括微观结构稳定性和析出行为的多组分热力学和动力学模型。关键的微结构设计理念基于通过L12型和DO22型沉淀的组合实现高性能换热器材料所需的卓越强度、高导热系数和更高的热机械强度(抗疲劳性)。在镍高温合金中，这两种类型的析出物以高度交互的方式形核和长大(“致密形态”)。Questek将通过了解这些沉淀物在受控共同演化过程中详细的化学(热力学)和弹性(应力)相互作用来利用这种“自组装”行为。该项目的目标是在换热器材料温度能力方面取得突破，使其服务温度能力(和热效率)显著高于以前实现的能力。该项目的更广泛影响/商业潜力是通过生产更高温度和更轻重量的换热器来跟上系统技术进步的步伐，这些换热器的需求越来越大。最先进的热交换器从根本上受到下一代高温合金供应的限制，有两个方面。首先，热交换器的重量受到现有材料厚度的限制。目前的工作温度要求厚表材料能够承受严重的热循环应力，从而产生较重的部件。能够在高温下承受更高应力的材料将使更薄的薄板能够在更薄的部分之间进行更好的热传递，从而减轻重量。此外，在较高的工作温度下，导热系数和热效率都得到了提高。热交换器部件的寿命和工作温度受到当前板状材料的温度能力的限制。材料性能的改进将对高温换热器的性能产生直接的好处。

This Small Business Innovation Research Phase I project will design and develop a new high performance Ni superalloy material for high temperature heat exchanger applications. The alloy design will leverage existing QuesTek efforts on Ni superalloy modeling, design, and prototyping, including multicomponent thermodynamic and kinetic models of microstructural stability and precipitation behavior. The key microstructural design concept is based around achieving the superior strength, high thermal conductivity, and elevated thermal-mechanical strength (fatigue resistance) required of high performance heat exchanger materials via a combination of L12-type and DO22-type precipitation. In Ni superalloys these two types of precipitates nucleate and grow in a highly interactive manner ("compact morphology"). QuesTek will harness this "self-assembly" behavior by understanding the detailed chemical (thermodynamic) and elastic (stress) interactions during the controlled co-evolution of these precipitates. The goal is a breakthrough in heat exchanger material temperature capability with significantly higher service temperature capabilities (and thermal efficiencies) than previously achievable.The broader impact/commercial potential of this project is to keep pace with improving system technology by producing higher-temperature and lower-weight heat exchangers that are increasingly in demand. State-of-the-art heat exchangers are fundamentally limited by the availability of next generation superalloys in two ways. First, the weight of heat exchangers is limited by the thickness of existing materials. Current operating temperatures require thick gauge material to withstand severe thermal cycle stresses resulting in a heavy component. Materials that could withstand higher stresses at elevated temperatures would enable thinner sheets resulting in weight savings in addition to better heat transfer across thinner sections. In addition, thermal conductivity and thermal efficiency are enhanced at higher operating temperatures. The life and operating temperature of heat exchanger components are limited by the temperature capability of currently-available materials in sheet form. Improvements in material performance would have direct benefits to high temperature heat exchanger performance.