Al-NiTi Metal Matrix Composites for Next Gen Zero CTE Materials: Modeling and Fabrication

Macro and microstructural modeling are used to design and fabricate Al-NiTi composite materials for thermal control applications. Ultrasonic additive manufacturing is used to make the composites. This enables the incorporation of trained and pre-strained NiTi wires into metals matrices at low formation temperature, which is not possible with fusion-based processes. The motivation to construct these composites lies in their low density compared to current low coefficient of thermal expansion (CTE) materials like invar. Successful implementation of these composites requires careful design, factoring in the characteristics of the processing as well as matrix-fiber interactions. To further understand composite behavior, rule-of-mixture (ROM) models are utilized for quick design iteration. Microstructure-based finite element (FE) simulations are also used to quantify composite strains and stresses and predict the composite CTE as a function of temperature. The relative benefits and disadvantages of the ROM and FE approaches are assessed through benchmarking, and guidelines are developed for optimal CTE composites.

This work is supported by the NSF I/UCRC on Smart Vehicle Concepts at The Ohio State University (www.SmartVehicleCenter.org) and by the Department of Energy, Office of Basic Sciences, DE-SC0001258 (John Vetrano, Program manager).