TY - JOUR

T1 - Evolution of nano-pores during annealing of technically pure molybdenum sheet produced from different sintered formats

AU - Jakob, Severin

AU - Lorich, Alexander

AU - Knabl, Wolfram

AU - Stark, Andreas

AU - Staron, Peter

AU - Clemens, Helmut

AU - Spörk-Erdely, Petra

N1 - Publisher Copyright: © 2022 The Authors

PY - 2023/1

Y1 - 2023/1

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85140652824&partnerID=8YFLogxK

U2 - 10.1016/j.ijrmhm.2022.106032

DO - 10.1016/j.ijrmhm.2022.106032

M3 - Article

VL - 110.2023

JO - International journal of refractory metals & hard materials

JF - International journal of refractory metals & hard materials

SN - 0263-4368

IS - January

M1 - 106032

ER -