Fabrication and Characterization of a Low Magnetic Zr-1Mo Alloy by Powder Bed Fusion Using a Fiber Laser

Process Optimization and Tailored Mechanical Properties of a Nuclear Zr-4 Alloy Fabricated via Laser Powder Bed Fusion

A nuclear Zr-4 alloy with a near full density was fabricated via laser powder bed fusion (LPBF). The influences of process parameters on the printability, surface roughness, and mechanical properties of the LPBF-printed Zr-4 alloy were investigated. The results showed that the relative density of the Zr-4 alloy samples was greater than 99.3% with the laser power range of 120-160 W and the scanning speed range of 600-1000 mm/s. Under a moderate laser power in the range of 120-140 W, the printed Zr-4 alloy possessed excellent surface molding quality with a surface roughness less than 10 µm. The microstructure of the printed Zr-4 alloy was an acicular α phase with an average grain size of about 1 µm. The Zr-4 alloy printed with a laser power of 130 W and a scanning speed of 400 mm/s exhibited the highest compression strength of 1980 MPa and the highest compression strain of 28%. The findings demonstrate the potential in the fabrication of complex Zr-4 alloy parts by LPBF for industrial applications.

Evaluation of cytocompatibility and osteoconductivity of Zr-14Nb-5Ta-1Mo alloy with MC3T3-E1 cells

The cytocompatibility and osteoconductivity of the Zr-14Nb-5Ta-1Mo alloy were investigated using a mouse osteoblastic cell line (MC3T3-E1) to promote the application of this newly developed alloy in dental/medical treatment. The initial cell-attached morphology was visualized by fluorescent staining, and cells cultured on the Zr alloy showed similar cell adhesion behavior to cells cultured on titanium (Ti). In our 5-day proliferation investigation, similar cell numbers were obtained with both Zr alloy and Ti. These results indicate that the cytocompatibility of Zr alloy is similar to that of Ti. In addition, the similar results in the evaluation of alkaline phosphatase (ALP) activity and staining of deposited calcium using alizarin red S with both Zr alloy and Ti indicated that the osteoconductivity of the Zr alloy is similar to that of Ti. Our results prove the good cytocompatibility and osteoconductivity of the Zr-14Nb-5Ta-1Mo alloy, enabling its promotion for use in dental/medical applications.

Effects of process parameters on the mechanical properties of additively manufactured Zr-1Mo alloy builds

In order to solve the artifact problem in magnetic resonance images, a low magnetic Zr-1Mo(wt%) alloy with high mechanical performance was successfully fabricated by laser powder bed fusion (L-PBF) using gas-atomized Zr-1Mo alloy powder. The as-built Zr-1Mo alloy showed superior strength and elongation compared to the as-cast Zr-1Mo alloy due to grain refinement and the inexistence of large casting defects. The microstructure of L-PBF-processed Zr-1Mo alloy builds was not sensitive to process parameters. On the other hand, morphology and distribution of defects, interstitials concentration, and crystallographic orientation comprehensively influenced the mechanical properties of the builds. Increasing interstitials concentration caused by increasing energy density render to increasing strength. Large pores caused by balling effect lead to a severe decrease of both strength and ductility of builds using high energy density (over 70.3 J·mm^-3) and high scanning speed (1050/1200 mm·s^-1). On the contrary, spherical pores possessing several microns in size has much less effect on mechanical properties than the large-size pores. There are two kinds of texture({1 1 0}_α texture and {1 1 0}_α+{1 0 2}_α bi-texture) were confirmed in this study. {1 1 0}_α texture contributed to the slight increase of elongation with increasing energy density in low scanning speed case (600/750 mm·s^-1) and the superior elongation of low scanning speed specimens compare to that of high scanning speed specimens in medium energy density range (about 48 J·mm^-3). From the viewpoints of the ultimate tensile strength(UTS) and elongation, it was found that an energy density of 84.4 mm·s^-1 with a scanning speed of 600 mm·s^-1 is preferable for the L-PBF-processed Zr-1Mo alloy in this study. These experimental results may provide direct guidelines regarding the applicability of Zr-1Mo alloy fabricated by L-PBF for biomedical applications.

A Review of Model Inaccuracy and Parameter Uncertainty in Laser Powder Bed Fusion Models and Simulations

This paper presents a comprehensive review on the sources of model inaccuracy and parameter uncertainty in metal laser powder bed fusion (L-PBF) process. Metal additive manufacturing (AM) involves multiple physical phenomena and parameters that potentially affect the quality of the final part. To capture the dynamics and complexity of heat and phase transformations that exist in the metal L-PBF process, computational models and simulations ranging from low to high fidelity have been developed. Since it is difficult to incorporate all the physical phenomena encountered in the L-PBF process, computational models rely on assumptions that may neglect or simplify some physics of the process. Modeling assumptions and uncertainty play significant role in the predictive accuracy of such L-PBF models. In this study, sources of modeling inaccuracy at different stages of the process from powder bed formation to melting and solidification are reviewed. The sources of parameter uncertainty related to material properties and process parameters are also reviewed. The aim of this review is to support the development of an approach to quantify these sources of uncertainty in L-PBF models in the future. The quantification of uncertainty sources is necessary for understanding the tradeoffs in model fidelity and guiding the selection of a model suitable for its intended purpose.

Improvement and Application of Zirconium Alloys

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