钼镧合金板材料舟的研制及其断裂行为分析

研究掺杂稀土镧的钼粉经压型、烧结、交叉换向轧制而成的钼镧合金板热冲压钼舟变温变载下的力学行为,探讨高温退火后析出物的弥散分布对钼镧合金板材力学性能的影响及加热制度对合金板材冲压成型性能的影响,分析料舟的断裂机制.研究表明,弥散分布的La2O3明显提高了钼板再结晶温度与力学性能,交叉轧制降低了板材纵向和横向力学性能的差异,有利于钼镧合金板的冲压成型；对2.8 mm厚Mo-1.0％La2O3合金板及冲压模具在550℃进行加热,将得到最大的冲压变形量；钼舟在18管炉内承受变温变载荷长期运行后,由于材料内部的空位迁移与滑移面上的位错滑移导致的韧窝撕裂,使料舟最终发生了宏观断裂.

Preparation of La-doped Molybdenum Boat and Analysis on Fracture Behavior

La2O3 doped Mo powder was pressed, sintered and cross rolled to prepare alloy plates. Then the plates were stamped to obtain molybdenum boat. The mechanical properties of the molybdenum boat were investigated under the condition of variable temperatures and loads. The influences of precipitate dispersive distribution on the mechanical properties and the influence of heating system on the stamping property were discussed for the alloy plates. And the fracture mechanism of the boat was analyzed. Results show that La2O3 of dispersive distribution increases markedly the recrystallization temperature and mechanical properties of the Mo plates. Cross rolling decreases the difference of mechanical properties between transversal and longitudinal directions, which is favorable for the stamping of Mo-La2O3 alloy plates. The maximum punch deformation can be reached when heating the 2.8 mm thick Mo-10%La2O3 alloy plate and stamping dies at 550 oC. After long-time operation of the boat in 18-tube furnace under the variable temperature and load condition, it is found that vacancy migration and dislocation slip result in dimple tear, and eventually lead to the macroscopic fracture of the molybdenum boat.