La元素在钼合金丝中赋存形式的时序性分析

Analysis on Time Sequence Characteristics of Occurrence Status of Lanthanum in Mo Alloy Wires

实验研究了变形态Mo-La合金丝的显微组织和力学性能对La含量的敏感性。实验结果表明,随着La含量的增加,变形态Mo-La合金丝的显微组织和力学性能的变化不大。这与退火态钼合金丝的强韧化效果随La含量变化而变化的规律不同。这一现象是La元素在钼合金丝中的赋存形式及其转化过程的时序性特征所致。Mo-La合金丝中,晶粒细化和位错钉扎的效果取决于La2O3颗粒的数量及其在钼基体中的弥散度。XRD衍射谱表明,在固-液掺杂MoO2还原制得的Mo-La合金粉末中,La元素并不是以La2O3,而是以La2Mo2O7的形式存在。La2O3颗粒是在Mo-La丝的整个工艺过程中,通过La3+离子与游离态氧原子结合,或La2Mo2O7分解的途径而逐步形成的。变形态Mo-La合金丝的制备过程不足以使La3+离子全部转变为La2O3,导致La2O3颗粒的生成过程滞后于制备过程,因此La含量对Mo-La合金丝的力学性能和显微组织的影响趋势不甚明显。

The sensitivity of the microstructure and mechanical properties of as-worked Mo-La alloy wires to the La content was studied.The results showed that with the increase of La content,the microstructure and mechanical properties of as-worked Mo-La alloy wires were scarcely improved,which was entirely different from the phenomenon that the toughening effect of annealed Mo-La alloy wires changed with the different La content.The fact was due to the occurrence status of La element in Mo alloy wires and the timing sequence characteristics during its transformation process.The grain refinement and dislocation pinning effects of Mo-La alloy wire depended greatly on the quantity of La2O3 particles and their dispersity in molybdenum substrate.XRD patterns showed that Mo-La alloy powders,which were obtained by the reduction of the solid-liquid doped MoO2,were composed of Mo atoms and La2Mo2O7.In the subsequent thermomechanical processing of as-worked Mo-La alloy wires,La2O3 particles were gradually generated by the combination between La3＋ ions and free oxygen atoms or the decomposition of La2Mo2O7.The thermomechanical processing was unable to make all of La3＋ ions became La2O3,resulting in that the generation of La2O3 particles lagged largely behind the termination of the whole process,so the microstructure and mechanical properties of the alloy wires were not obviously sensitive to the La addition level.