Microstructure Controlled Forming of High Performance Light Metals by Combined Loading under compression and Torsion

本课题组开发的压扭复合成形技术，可以在不改变金属形状的前提下，将大的塑性应变引入金属中。将成形的优点应用于一些轻金属的显微组织控制、金属间化合物的机械合金化合成和纯铝的细化。研究结果如下：1.在纯铝和纯钛的成形粉末混合物中发现了机械合金化效应，通过该成形工艺可以合成金属间化合物Al_3Ti。虽然Al_3Ti的合成只在试件的加载侧观察到，但通过改变成形温度、压力和循环次数，合成区可以扩展。所合成的金属间化合物可以同时与金属连接。纯铝的晶粒细化1.在10μm以下，压扭成形可以细化纯铝铸锭中的100μm的晶粒。虽然细化作用仅限于试件的加载侧，但通过控制加载条件，细化区域可以扩展。较低的温度和较低的试件高度有利于细化。

The compressive -torsion forming, which had be developed by the head investigator, is enable to introduce large plastic strain into a metal without changing its shape. The advantage of the forming was applied to control microstructures of some light metals, and mechanical alloying synthesis of an intermetallic compound and grain refinement of a pure aluminum. The results were as follows ;<< Synthesis of an intermetallic compound >>1. A mechanical alloying effect was found in the forming powder mixture of pure aluminum and titanium, and an intermetallic compound Al_3Ti could be synthesized by the forming process.2. Although the synthesis of the Al_3Ti was observed only in loading side of a specimen, the synthesized region can spread by changing in forming temperature, pressure and cycle.3. The synthesized intermetallic compound can be joined simultaneously with metals.<< Grain refinement of a pure aluminum >>1. Grains of 100 μm in the pure aluminum ingot can be refined under 10 μm by the compressive -torsion forming.2. Although the grain refinement was limited only in loading side of a specimen, the refined region can spread by controlling some loading conditions.3. Low temperature and low specimen height are effective to the refinement.