机械合金化制备Fe-10%Ni合金研究

采用纯Fe粉和Ni粉利用高能卧式搅拌球磨机制备了Fe-10%Ni(质量分数,下同)合金,利用X射线衍射(XRD)、扫描电子显微镜(SEM)、差热分析(DTA)研究了球磨粉末的相组成、形貌和热稳定性,并对其热压烧结的块材进行了组织分析与性能测试。结果表明,在球磨机转速400 r/min,球料比20:1条件下,球磨8 h后,Ni原子完全固溶在Fe原子晶格中,形成体心立方结构Fe(Ni)过饱和固溶体,延长时间到16 h,球磨粉末颗粒尺寸更均匀细小,但仍为体心立方Fe(Ni)固溶体。对球磨16 h的合金粉末在500~800℃进行退火处理,发现粉末结构稳定,仍为体心立方Fe(Ni)固溶体。对球磨16 h的合金粉末进行热压烧结,发现950℃下烧结块材中出现少量fcc结构的Fe(Ni)固溶体相,而继续在970℃复烧后则完全转变为面心立方结构的Fe(Ni),但950℃热压烧结块材的强度和延伸率高于970℃复烧的块材,原因在于无压复烧块材中产生氧化物和孔洞。

Research on Fe-10%Ni Alloy Synthesized by Mechanical Alloying

Fe-10%Ni alloys were synthesized in a high energy horizontal rotary ball mill from pure element Fe and Ni powders. Phase constitution, shape and thermal stability of the milled powders were characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA), respectively. And microstructure and properties of bulks prepared by hot-press sintering with milled powders as starting materials were analyzed and tested. Results indicate that under the condition of a milling speed of 400 r/min and a ball-to-powder mass ratio of 20:1, Ni fully solubilizes in Fe, which forms a supersaturate solid solution of Fe(Ni) with a body-centered cubic structure. Particles of the powder milled up to 16 h are more homogeneous and finer than those of the powder milled for 8 h, but phase of the powder is still Fe(Ni) solid solution. The alloy powder milled for 16 h were annealed in the temperature range between 500 and 800 oC. It is found that structure of the powder after annealing is stable and no phase transformation occurs in the powder. Phase of the powder is still Fe(Ni) solid solution. When the alloy powders milled for 16 h were treated by hot pressed sintering at 950 oC, a little Fe(Ni) solid solution with a face-centered cubic structure is found in the bulks. If the bulks that previously were treated by hot-press sintering at 950 oC and cooled to room temperature were subsequently sintered at 970 oC again, the phase of the powders completely transforms to Fe(Ni) solid solution with a face-centered cubic structure. However, the strength and ductility of bulks treated by hot-press sintering at 950 oC are superior to those of bulks by subsequent sintering at 970 oC, because oxide and holes are produced in resintered bulks without pressure.