Grain Refinement of Al-Mg alloy by Hydrogenation Treatment and Its mechanism Analysis

晶粒细化作为提高材料强度和超塑性行为的一种手段受到人们的重视。本研究的主题已经表明，在5083 Al（Al-Mg）合金中，这种具有细晶粒尺寸的显微组织可以通过在加工过程中施加极大的塑性应变来实现，该塑性应变利用高温下的吸氢和脱氢等特性。2001年至20011年，在773 K下进行了14. 5 h的氢化处理，氢化产物MgH_2作为位错堆积源，有利于合金中高密度位错结构的形成。4ks和氢气气氛下0. 4MPa。氢化后的试样进行了90%的大变形量冷轧，用X射线衍射分析和氚技术的透射电镜观察证实了氢化物的存在，氢化物的诱导氢含量约为107×10 关于我们 ^2质量%。然后，为了获得细晶粒尺寸的材料，进行热处理以在盐浴中进行快速再结晶。最后在523 K真空（0。1 Pa）下脱氢30小时。残余氢含量为0. 9×10^2质量%。氢化样品显示出波浪形的变形痕迹，以防止容易变形，并显示出更细的晶粒结构（2。5 μ m）。屈服强度和抗拉强度提高1. 2：通过X射线衍射分析和使用氚技术的TEM观察确定了氢化物的存在。2001年至20021年：对于氢化试样的超塑性行为，在625 K和5×10^3 s^1应变速率下，延伸率约为300%。这些样品的疲劳强度为1。比未氢化样品高8倍。然而，在腐蚀测试中，这些样品没有显示出显著的改善。少

The grain refinement is noticed, as method to enhance the strength of materials and to be appeared the superplasticity behavior. The subject of this study has shown that, in 5083AI (AI-Mg) alloy, this microstructure with fine grain size can be achieved by imposing extremely large plastic strains during work processing using characteristic properties such as hydrogen absorption and dehydrogenation at high temperature. Hydride precipitations MgH_2 obtained in this treatment were more useful to develop the high-density dislocation structure in alloy as dislocation pileup sources.The following results of this study were obtained :2001〜20011 : Hydrogenation treatment was carried out in 773K for 14. 4ks and in hydrogen atmosphere under 0. 4MPa. The hydrogenated samples were carried out heavy cold rolling with the 90% reduction ratio An existence of hydrides was determined by an X-ray diffraction analysis and TEM observation using tritium technique An induced hydrogen content was about 107×10 … More ^2 mass%. Then, to obtain the fine grain sized material, heat treatment was performed to do rapid recrystallization in salt bath. The materials were finally heated at 523K in vacuum (0. 1Pa) for dehydrogenation for 30hr. The residual hydrogen content was 0. 9×10^2 mass%. The hydrogenated samples indicates wavy deformation traces to be prevented easy deformation and shows more fine grain structure (2. 5 u m). Yield strength and tensile strength increased more than 1. 5times in comparison with that of non-hydrogenated specimen.2 : An existence of hydrides was determined by an x-ray diffraction analysis and TEM observation using tritium technique. The grain size is finer with induced hydrogen content.2001〜20021 : For superplasticity behavior of hydrogenated specimen, elongation was about 300% at 625K and 5×10^3 s^1 strain rate. The fatigue strength of these samples was 1. 8times higher than that of non-hydrogenated samples. However, in corrosion test, these samples did not indicate remarkable improvement. Less