Evaluation of tensile property and strengthening mechanism of molybdenum alloy bars doped with different ultrafine oxides
(1. Henan Key Laboratory of High-temperature Structural and Functional Materials, Henan University of Science and Technology, Luoyang 471003, China;
2. National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials, Henan University of Science and Technology, Luoyang 471003, China;
3. Beijing National Innovation Institute of Lightweight Ltd., China Academy of Machinery Science and Technology, Beijing 100089, China)
2. National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials, Henan University of Science and Technology, Luoyang 471003, China;
3. Beijing National Innovation Institute of Lightweight Ltd., China Academy of Machinery Science and Technology, Beijing 100089, China)
Abstract: Three kinds of molybdenum alloy are doped with 2.0 wt.% different ultrafine oxide particles (Al2O3, ZrO2 and La2O3) via hydrothermal synthesis, co-precipitation, co-decomposition, powder metallurgy, and rotary swaging. Three nano-oxides refine molybdenum grains by more than 70% and change the fracture modes from brittle fracture to ductile fracture, thereby dramatically improving the integrated mechanical properties of the alloys. Moreover, the trade-off between strength and ductility is offset. Mo-ZrO2 alloy has the highest strength and plasticity, which is attributed to fine ZrO2 particles and a semi-coherent interface between ZrO2 and molybdenum matrix. Moreover, a quantitative strengthening model correlating dislocation density, oxide volume fraction and size, and molybdenum grain size is established.
Key words: molybdenum alloy; Al2O3; ZrO2; La2O3; strength-elongation product; strengthening model