Effects of Ce Addition on Mechanical Properties and Microstructures of Mo Alloy Wires

The effects of Ce addition on mechanical properties and microstructures of Mo-Ce alloy wires were investigated. The results show that the yield strength (R-p), tensile strength (R-m) and elongation to failure (A%) of Mo-Ce alloy wires were sensitive to the Ce content. When the Ce content was less than 0.03 wt%, R-p, Rm and A% did not change significantly as comparing with the unalloyed molybdenum wires; when the Ce content was ranging from 0.06 to 0.09 wt%, R-p and Rm gradually increased, and the decreasing of A% was accompanied; when the Ce content was ranging from 0.09 to 0.12 wt%, the maximum A% and moderate R-p and Rm were obtained; when the Ce content was ranging from 0.15 to 0.3 wt%, R-p, Rm and A% decreased simultaneously. The optical microstructures of as-sintered Mo-Ce alloys show that the grain sizes of Mo-Ce alloys were 20-30 mu m, which were almost equivalent to one quarter of those of unalloyed molybdenum. In addition, the TEM and XRD analyses show that Ce element homogeneously dispersed in the intra- and inter-granular molybdenum substrate in the form of CeO2 particles during the whole preparation processing. Due to that the lattices of CeO2 particles were partly coherent with the molybdenum matrix, they not only had the significant grain refinement and dispersion strengthening effects, but also served to inhibit the brittle-to-ductile transition behaviors of Mo alloys during the subsequent thermo-mechanical procedure. Therefore, the comprehensive mechanical properties of Mo-Ce alloys are much superior to those of the other oxide-dispersion-strengthened molybdenum alloys.