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

该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热交换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、设计和原型制作方面的现有成果，包括微观结构稳定性和沉淀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是基于通过L12型和DO 22型沉淀的组合实现高性能热交换器材料所需的上级强度、高导热性和提高的热机械强度（抗疲劳性）。在镍超合金中，这两种类型的沉淀物以高度相互作用的方式成核和生长（“致密形态”）。QuesTek将通过了解这些沉淀物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。该项目的目标是在热交换器材料的温度能力方面取得突破，其工作温度能力（和热效率）比以前可实现的要高得多。该项目更广泛的影响/商业潜力是通过生产需求日益增长的更高温度和更轻重量的热交换器来跟上改进系统技术的步伐。最先进的热交换器在两个方面受到下一代高温合金可用性的根本限制。首先，热交换器的重量受到现有材料厚度的限制。目前的工作温度需要厚规格材料来承受严重的热循环应力，从而导致重部件。能够在高温下承受更高应力的材料将能够实现更薄的片材，除了在更薄的部分上更好地传热之外，还可以节省重量。此外，在较高的工作温度下，导热性和热效率得到增强。热交换器部件的寿命和操作温度受到当前可用的片材形式的材料的温度能力的限制。材料性能的改进将对高温热交换器性能具有直接益处。

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.