Evolution of nano-pores during annealing of technically pure molybdenum sheet produced from different sintered formats

Severin Jakob, Alexander Lorich, Wolfram Knabl, Andreas Stark, Peter Staron, Helmut Clemens, Petra Spörk-Erdely

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Molybdenum is a refractory metal with no phase transformation in the solid state and a high melting point. It is therefore an excellent structural material for various high temperature applications. Especially in this field of operation, significant creep resistance is essential. To achieve this, a microstructure with grains in the range of millimeters is desired. However, as demonstrated in the present study, the onset temperature for secondary recrystallization, which would lead to a beneficial grain size, is among other things dependent on the initial dimensions of the sintered part. One possible reason for the different microstructural evolutions is the influence of residual pores in sub-micrometer size. Sheets were thus fabricated via three different production routes employing the same initial Mo powder to exclude chemical variation as an influencing factor. The samples were investigated by in-situ small-angle X-ray scattering at a synchrotron radiation source with two different heating rates. Additionally, selected annealed samples were studied ex-situ with high energy X-rays. The apparent volume fraction of pores is compared to a volatilization model for the vaporization of typical accompanying elements and the induced thermal expansion.

Original languageEnglish
Article number106032
Number of pages7
JournalInternational journal of refractory metals & hard materials
Issue numberJanuary
Early online date20 Oct 2022
Publication statusPublished - Jan 2023

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