Theses and Dissertations

Date of Award

7-1-2025

Document Type

Thesis

Degree Name

Master of Science in Engineering (MSE)

Department

Manufacturing Engineering

First Advisor

Anil Srivastava

Second Advisor

Nazmul Ahsan

Third Advisor

Farid Ahmed

Abstract

Powder spreading marks a crucial step in the Laser powder bed fusion process, directly impacting the powder bed uniformity and paving the way for subsequent stages in the process. The laser powder bed fusion process depends heavily on the composition of the metallic powder feedstock. While most existing studies focus on pre-alloyed powders, limited work has explored the use of elemental powder blends as feedstock as used in in-situ alloying. Pre-alloyed powders are often costly, exhibit irregular morphologies and offer limited flexibility in material selection. This study uses Discrete Element Method (DEM) simulations to investigate how variations in material density and particle size of elemental powders influence bed uniformity, composition homogeneity and packing density. For mixed powder beds, consisting of 15- 45µm particles, findings showed that systems with large density differences such as aluminum and tungsten (Al-W) exhibited significant segregation and non-uniform spreading, while those with closer densities such as Al-Fe and Al-Ni achieved better layer uniformity and packing density. Finer particles of aluminum were able to compensate for density differences in Al-W blend with larger size of tungsten, 30µm and 45µm W, and enhanced packing density and uniformity of the powder bed. By modeling both the mixing and spreading process, this research provides valuable insights into mixed elemental powder spreading behavior. The findings contribute to the potential of using elemental blends to expand material selection and widen the scope of applications of the powder bed fusion process.

Comments

Copyright 2025 Alfred Kofi Apianing Achenie. All Rights Reserved. https://proquest.com/docview/3313403339

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