Ternary composite tungsten electrode should be studied to know its lamination mechanism during sintering. A tertiary RE-W electrode with a diameter of 16mm was used to do the research.
The morphologies and phases of the sintered billets were investigated by SEM and XRD, respectively. The composition of the second phase particles was analyzed by EDAX. The percentages of rare earth oxides in different regions were detected by ICEP-AES. The distribution of RE elements at the fracture was detected by EPMA. The results show that:
1. The distribution of RE elements across the fracture section is not uniform;
2. The second phase particles are mostly distributed at grain boundaries;
3. The number and grain size of the second phase particles of RE elements and tungsten particles are different between the center and the edge. It is found out that the diffusion and volatilization of RE elements not only lead to the non-uniform composition but also aggravate the non-uniformity of the structure caused by temperature gradient, thus leading to lamination phenomenon finally.
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