Jae Yu

Date of Award

3-2022

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Ryan A. Kemnitz, PhD

Abstract

Selective laser melting (SLM) of refractory metals has been of high interest in research due to the metals’ potential desirable characteristics in aeronautical and space applications. In particular, molybdenum and tungsten have been the focus of several studies in the search for high temperature and high strength purposes in applications like supersonic aircraft, re-entry vehicles, nuclear fission, power generation, and other space systems. However, there is still a significant knowledge gap to process defect-free alloys and making use of them in practical engineering functions. The aim of this study is to characterize the relationship between the microstructure and mechanical properties of the additive manufacturing (AM) of molybdenum and 30% tungsten system (Mo-30W) specimens and interpret how unique microstructural characteristics and defects relating to AM of Mo-30W alloys influence the fracture behavior. This study provides qualitative and quantitative approaches to characterize microstructure and mechanical properties of the various Mo-30W by evaluating the effects of print chamber atmosphere, print speeds, build orientations, and post processing heat treatments through means of mechanical tests, chemical composition analysis, porosity analysis, and fracture surface assessment.

AFIT Designator

AFIT-ENY-MS-22-M-319

DTIC Accession Number

AD1175640

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