Optimization of Laser Powder Bed Fusion Process Parameters for Printing Zr-based Bulk Metallic Glass by an In-House Developed Semi-Analytical Model

Emanuel Gingl

Research output: ThesisMaster's Thesis

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Abstract

Laser powder bed fusion (LPBF) is a revolutionary technology that has recently been recognized as an ideal manufacturing method for Zr-based bulk metallic glasses (BMGs). Current state-of-the-art manufacturing methods such as arc-melting, and copper mold casting, have limitations in realizing complex geometries, while LPBF offers more flexibility. Moreover, LPBF allows for a fine balance between the generation of intricate features and maintaining appropriate cooling rates throughout the process. This study focuses on the optimization of process parameters of a particular, additively manufactured Zr-based alloy, AMZ4, due to its superior qualities and commercial availability, with the goal to improve its mechanical and thermal properties. A preliminary parameter selection analysis is carried out, revealing the relationship between energy density and porosity. Several experiments, including dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM), are subsequently conducted on the samples manufactured by LPBF. Valuable insight is gained regarding the glass transformation characteristics, ß-relaxation behavior, and microstructure of the samples. An in-house developed, semi-analytical simulation algorithm is created to calculate the thermal history for single-track, as well as multi-track, multi-layer LPBF simulations. The model is coupled with a function which evaluates the degree of crystallinity using the forward Euler method, providing vital information regarding presence of crystal phases within the microstructure. This allows for a significant reduction in the amount of required time-intensive laboratory experiments. Of the ten samples tested, the study finds that energy densities of less than 50J/mm3 are required to achieve optimal thermal stability and that energy densities lower than 40J/mm3 increase amorphous content. The outcomes support the theoretical claims that lower energy densities lead to increased amorphous content, which in turn leads to improved mechanical properties including ductility. The work concludes that Zr-based BMGs are promising engineering materials with potential applications in the medical industry, and additive manufacturing methods like LPBF can enhance the BMG manufacturing process by allowing for the generation of intricate features and maintaining appropriate cooling rates. The research findings aim to contribute to the broader applicability of AMZ4 and accelerate the development of similar advanced engineering materials.
Translated title of the contributionOptimierung der Prozessparameter für das Laserstrahlschmelzen von massivem metallischen Glas auf Zr-Basis mithilfe eines halbanalytischen Simulationsmodells
Original languageEnglish
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Eckert, Jürgen, Supervisor (internal)
Award date15 Dec 2023
DOIs
Publication statusPublished - 2023

Bibliographical note

no embargo

Keywords

  • Materials Science
  • Additive Manufacturing
  • Bulk Metallic Glasses
  • Simulation
  • Energy Density
  • Crystallinity
  • Dynamic Mechanical Analysis
  • Differential Scanning Calorimetry
  • MATLAB
  • Ductility

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