Study on the sintering properties of Mo–La2O3 nano-powders prepared by solution combustion method
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摘要: 利用溶液燃烧法制备氧化镧（La2O3）掺杂Mo粉前驱体，对前驱体粉末还原、烧结，研究La2O3掺杂量（质量分数）对Mo–La2O3合金性能的影响。结果表明，前驱体粉末在700 ℃下氢气气氛中还原，得到平均晶粒尺寸在100～220 nm的La2O3掺杂Mo粉。Mo–La2O3粉末经过1600 ℃放电等离子烧结后相对密度达95%以上，但随着La2O3掺杂量的提升，其相对密度逐渐降低。随着La2O3掺杂量的增加（质量分数在0～1.0%范围内），显微硬度先上升后下降。在La2O3掺杂量为0.7%时，Mo晶粒尺寸为500 nm左右，材料显微硬度最高，达到了HV0.2 564。Abstract: Molybdenum (Mo) precursor powders doped by lanthanum oxides (La2O3) were prepared by the ultra-rapid solution combustion synthesis method using the low-cost and non-toxic starting materials, and the precursor powders were reduced and sintered. The effect of La2O3 doping content (mass fraction) on the properties of Mo–La2O3 alloys was studied. The results show that, the La2O3 doped molybdenum powders with the average particle size of 100~220 nm are obtained by the reduction of the combustion precursor in the hydrogen atmosphere at 700 ℃. The relative density of La2O3 doped molybdenum alloys sintered at 1600 ℃ is over 95%. With the increase of La2O3 doping content (mass fraction in the range of 0~1.0%), the microhardness increases firstly and then decreases. When the La2O3 doping content is 0.7%, the grain size of Mo is about 500 nm, and the microhardness of the materials reaches the highest as HV0.2 564.
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图 1 La2O3掺杂量对前驱体粉末显微形貌的影响：（a）0；（b）0.3%；（c）0.7%；（d）1.0%
Figure 1. Effect of La2O3 doping content (mass fraction) on the microstructure of the precursor powders: (a) 0; (b) 0.3%; (c) 0.7%; (d) 1.0%
图 2 掺杂不同质量分数La2O3的Mo粉700 ℃还原产物显微形貌：（a）0；（b）0.3%；（c）0.7%；（d）1.0%
Figure 2. SEM images of the reduction products of the Mo powders doped by La2O3 in different mass fraction: (a) 0; (b) 0.3%; (c) 0.7%; (d) 1.0%
图 3 掺杂不同质量分数La2O3的Mo粉700 ℃还原产物X射线衍射图谱
Figure 3. XRD patterns of the Mo powders doped by La2O3 in different mass fraction after reduction at 700 ℃
图 4 掺杂质量分数1.0%La2O3的Mo粉在700 ℃还原产物的扫描电子显微形貌（a）和对应的能谱分析（b）
Figure 4. SEM image (a) and the corresponding EDS analysis (b) of the Mo powders doped by 1.0%La2O3 after reduction at 700 ℃
图 5 Mo–0.7La2O3前驱体粉末透射电子显微镜照片：（a）低倍；（b）高倍
Figure 5. TEM images of the Mo–0.7La2O3 precursor powders: (a) low magnification; (b) high magnification
图 6 经1600 ℃烧结后不同质量分数La2O3掺杂Mo合金的断口形貌：（a）0；（b）0.3%；（c）0.7%；（d）1.0%
Figure 6. Fracture morphology of the Mo alloys doped by La2O3 in different mass fraction sintered at 1600 ℃: (a) 0; (b) 0.3%; (c) 0.7%; (d) 1.0%
图 7 1600 ℃烧结Mo–La2O3合金相对密度随La2O3质量分数变化
Figure 7. Relative density of the Mo–La2O3 alloys doped by La2O3 in different mass fraction sintered at 1600 ℃
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