Formation of bulk material of metastable phase by solid-state reaction of complex ultra fine powders.

本研究对金属超细粉的烧结进行了两年的研究。该研究的特点是超细粉体从生产到烧结在一个连续的设备中处理。特别是采用本课题组研制的惰性气体清洗系统，可将氧气和水分保持在较低的状态。主要研究结果如下：1.惰性气体净化系统、O_2和H_2O检测器与格罗夫箱相连，格罗夫箱与超细粉体生产系统直接相连.降低反应室压力和原料粉进料速率，可以减小超细粉体的粒径.在相同烧结温度下，加压烧结的超细粉体密度高于无压烧结的超细粉体密度。在相同烧结密度条件下，烧结温度降低了200 K 关于我们 压力（300 MPa）下的热稳定性比无压力下的好.烧结超细粉体的硬度随烧结过程的进行而增大，随晶粒长大而减小。镍和铜的最大硬度分别为500 Hv和250 Hv，比铸态分别高出7个和4个9.烧结超细粉体的硬度与晶粒尺寸的-1/2次方成正比，这表明Hall-Petch关系成立.从理论上考虑了晶粒尺寸对烧结速率和晶粒生长速率的影响，结果表明，随着晶粒尺寸的减小，烧结速率高而晶粒生长速率低的温度区域增大.在制备每种粉末后，使用超声设备尝试混合不同的超细粉末。然而，由于聚集，没有实现微尺度混合。为了获得均匀的混合，最好的方法被认为是在蒸汽条件下混合材料。设计了一种新型双等离子体接触式超细粉体制备系统。少

In the present investigation the sintering of matal ultra fine powders have been studied for two years. This study was characterized by the fact that the ultra fine powders were handled in one continuous equipment from production to sintering. Especially using the inert gas cleaning system obtained by the present grant, the O_2 and moisture content was kept in quite low state. The main results obtained were as follows.1. The inert gas cleaning system, O_2 and H_2O detectors were censer attached to the grove box and this grove box was directly connected with the ultra fine powder producing system.2. The diamer of ultra fine powder was reduced with reducing the chamber pressure and the material powder feeding rate.3. The density of sintered ultra fine powder at the same sintering temperature was higher when sintered under the pressure than that without pressure at the same sintering temperature. The sintering temperature which gives the same sintering density was 200K lower when sintered … More for that under pressure (300MPa) than that without pressure.4. The hardness of sintered ultra fine powder increases with the progress of sintering and decrease with the progress of grain growth. The maximum hardness obtained was 50OHv for Ni and 25OHv for Cu, which were 7 and 4 nines larger than those of casted.5. The hardness of sintered ultra fine powders was proportional to -1/2 power of the grain size and this indicates that the Hall-Petch relation is held.6. The theoretical consideration of the effect of grain size to the sintering rate and grain growth rate indicates that the temperature region where sintering rate is high and grain growth rate is low increases with the decrease in grain size.7. The mixing of different ultra fine powders after production of each powder was tried using ultrasonic equipment. However microscale mixing was not achieved because of the aggregation. To obtain uniform mixing the best method wascon sidered to mix the material in the vapor condition. A new type double plasma touch ultra fine powder production system was designed. Less