Microstructure and mechanical properties of molybdenum-titanium-zirconium-carbon alloy TZM processed via laser powder-bed fusion
Graphical abstract
Section snippets
State of the art
The successful use of materials in high-temperature applications – for example, in the aerospace and medical industries or for metal working tools – requires materials that have excellent high-temperature properties. Molybdenum has a high melting point, a low thermal expansion coefficient, a high thermal conductivity, and an excellent high temperature strength and creep resistance [1]. The molybdenum alloy TZM has demonstrated its potential for use in applications where robust high-temperature
Experimental procedure
Spherical, pre-alloyed TZM powder with metallic purity >99.9% produced by gas atomization was used in this study. The powder was fractioned by sieving with a mesh size of 63 μm. The particle size was measured using a MALVERN MASTERSIZER 3000 laser diffraction particle-size analyzer; the carbon content was measured by applying the combustion method using an LECO CS-230; the oxygen, hydrogen, and nitrogen contents were measured by carrier gas hot extraction using an LECO TC-500; and the titanium
Macro- and microstructure
Fig. 1 shows the morphology of the spherical, gas atomized TZM powder. Several particles exhibit satellites or are irregularly shaped. The powders' physical and chemical properties are listed in Table 2. The contents of the alloying elements titanium, zirconium, and carbon in the powder are 5045 ± 29 μg/g, 861 ± 23 μg/g, and 257 ± 2 μg/g, respectively. The gas contents in the powder are 388 ± 36 μg/g for oxygen, < 5 μg/g for nitrogen, and < 1 μg/g for hydrogen.
Table 3 shows the density and
Conclusions
The present study constitutes the first detailed analysis of processing TZM via LPBF. Dense and crack-free samples were produced. The following conclusions are drawn:
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TZM was produced via LPBF with a density of 99.7% of the theoretical density and a crack-free microstructure.
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Epitaxial grain growth leads to elongated grains toward the BD with an aspect ratio of 0.4 ± 0.17. A weak <111> fiber texture parallel to the BD is formed.
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Mo2C precipitates are found in the grain interior.
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Oxygen impurities
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
The authors would like to thank the Austrian Research Promotion Agency (FFG) for supporting the research [DB-NR: 235364].
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