Development of Ultrafine-Grained Metallic Materials Using Intense Plastic Straining Technique

利用强塑性应变技术对金属材料的晶粒细化进行了尝试。本研究涵盖了精炼过程中微观组织演变和静态退火过程中微观组织稳定性的检查。结果总结如下：1。通过改变模具中通道弯曲的角度来控制材料中引入的应变。结果表明，单次施加大应变比多次施加大应变时，相邻晶粒间取向偏差较大的晶粒增多。在Al中添加Mg对晶粒细化有效：Al为-1 μ m， Al-1%Mg为-0.5 μ m， Al-3%Mg为-0.2 μ m。当Al中添加0.12%Zr时，晶粒尺寸几乎没有变化，但在300（比Al高100）℃的温度下，晶粒尺寸为-1 μ m的细小晶粒结构仍然保持稳定。结果表明，Al_3Zr颗粒的分散是抑制晶粒生长的重要因素。Cu.5的晶粒尺寸为-0.3 μ m。高分辨率电镜观察表明，Cu的晶界结构比Al的晶界结构更不规则。Cu的熔点比Al的熔点高，因此Cu的恢复效果较小。结果表明，强塑性应变技术是制备超细晶材料的一种有效方法。对于合金材料或熔点较高的金属，晶粒细化更为有效。

Grain size refinement of metallic materials has been attempted using an intense plastic straining technique. This study has covered examinations of microstructural evolution during refining process and of microstructural stability during static annealing. The results are summarized as follows.1. The strain introduced in the material was controlled by changing the angle where a channel was bent in a die. It was found that the grains with large misorientations between neighboring grains increased when a large strain was imposed by one pressing rather than by many pressings.2. Addition of Mg to Al was effective to grain size refinement : -1 mum for Al but -0.5 mum for Al-1%Mg and -0.2 mum for Al-3%Mg.3. There was almost no effect on the grain size when 0.12%Zr was added to Al, but the fine grain structure with a grain size of -1 mum remained stable up to a temperature of 300ﾟC which is higher by 100ﾟ than for Al. It was found that the presence of a fine dispersion of Al_3Zr particles was important for the inhibitation of significant grain growth.4. A grain size of -0.3 mum was attained in Cu.5. High-resolution electron microscopy revealed that the grain boundary structure exhibits more irregular configuration in Cu than in Al. It was concluded that the effect of recovery is less in Cu as the melting point of Cu is fairly higher than that of Al.6. It was concluded that the intense plastic straining technique is a useful method for the production of ultrafine grained materials. The grain size refinement is more effective for alloyed materials or for metals with higher melting temperatures.