First Advisor

Chien Wern

Term of Graduation

January 2026

Date of Publication

6-1-2026

Document Type

Thesis

Language

English

Subjects

Additive Manufacturing, CMD Powders, Cold Spray, Nickel Aluminum Bronze

Physical Description

1 online resource ( pages)

Abstract

Nickel-aluminum bronze (NAB) is widely used for maritime components but is traditionally limited to casting due to its complex microstructure. Fine β′ phase formation in NAB is governed by the solid-state transformation of the high-temperature β phase during cooling. This ordered martensitic β′ forms via diffusionless transformation, contributing to brittleness. Conventional metal additive manufacturing (AM) techniques, such as Laser Powder Bed Fusion and Directed Energy Deposition, experience high in-process cooling rates that promote fine β′ formation, compromising mechanical performance. Powder production similarly suffers from β′ formation, often requiring additional processing. Cold Mechanically Derived (CMD) powders, produced from wrought feedstocks, retain many desirable properties of the wrought state and have recently gained commercial availability. C63000 NAB has been successfully produced in CMD form.Cold Spray Additive Manufacturing (CSAM) is a solid-state AM technique that accelerates powders through a supersonic nozzle, bonding particles via extreme plastic deformation. CSAM avoids high-temperature transformations, mitigating β′ formation and associated cracking. This work establishes a process window for C63000 NAB CMD powders in a nitrogen-based CSAM system, enabling industrial adoption. A 3×3×3 Design of Experiments was performed to evaluate the effects of spray temperature, pressure, and stand-off distance on as-sprayed density, targeting initial densities ≥90%. Temperature and pressure were identified as the dominant factors affecting density. Microstructure evaluation identified the subsequent material state and enabled direct comparison with a typical incoming wrought and CMD feedstock. By defining a CSAM process window for NAB, this study enables fabrication and repair of maritime components without casting and lays the foundation for future mechanical property and microstructure evaluation and industrial adoption.

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Available for download on Saturday, June 26, 2027

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