Date of Award

2026-05-01

Degree Name

Master of Science

Department

Materials Science and Engineering

Advisor(s)

Brian E. Schuster

Abstract

Hybrid additive manufacturing of tungsten-nickel alloys, combining vat photopolymerization (VPP) for patterning with custom thermo-hydrogen post-processing for reduction and densification, has emerged as a promising route for fabricating complex, high-resolution tungsten architectures. However, fabrication of tungsten via this hybrid AM technique remains challenging due to poor densification and significant defect formation during debinding and sintering. In this work, these limitations were addressed using nickel as a sintering aid in combination with controlled thermal processing conditions. Existing studies on activated sintering of tungsten typically focus on a single composition or sintering condition, limiting understanding of the combined effects of composition and temperature. This study systematically investigates the influence of nickel content and sintering temperature on densification, defect formation, and microstructural evolution in tungsten-based architectures fabricated via hybrid AM. Tungsten-nickel (W-Ni) compositions ranging from 50W:0.5Ni to 50W:3Ni (atomic ratio) were fabricated and sintered at 1350 °C and 1500 °C. Lower nickel contents led to incomplete densification and microcracking within tungsten grains, whereas higher nickel contents yielded denser structures with interconnected nickel networks and significant grain growth. Overall, the results demonstrate a clear trade-off: increasing nickel content enhances densification while simultaneously promoting grain coarsening. Sintering temperature further amplified these effects by increasing diffusion rates and the mobility of the liquid phase. These findings establish nickel content as a critical parameter governing densification, defect formation, and microstructural evolution in hybrid AM tungsten systems.

Language

en

Provenance

Received from ProQuest

File Size

61 p.

File Format

application/pdf

Rights Holder

Jose Miguel Gonzalez

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