STRUCTURE OF Al-Mn-Zn-Mg ALLOY POWDER

ＳＴＲＵＣＴＵＲＥＯＦＡｌ－Ｍｎ－Ｚｎ－ＭｇＡＬＬＯＹＰＯＷＤＥＲ￥ＷＵＬｉｊｕｎ;ＺＨＡＯＬｉｈｕａ;ＹＡＮＧＱｉａｏｑｉｎ;ＬＩＳｈａｏｌｕ;ＬＩＸｉｅｑｉａｎ（ＭａｔｅｒｉａｌｓＲｅｓｅａｒｃｈａｎｄＴｅｓｔＣｅｎｔｒｅ,ＨｕｎａｎＵｎｉｖｅｒ...     

Al65Cu20Cr15准晶颗粒／铝基复合材料中二十面体准晶扩散相变

用ＪＣＸＡ－７３３型电子探针,Ｈ－８００型透射电镜、Ｄ／ｍａｘ－ⅢＡ型Ｘ射线衍射仪等研究了Ａｌ６５Ｃｕ２０Ｃｒ１５准晶颗粒／铝基复合材料中的准晶颗粒在热压过程中扩散相变。     

畸变Al-Li-Cu准晶单晶对称性的研究

本文给出了畸变Al-Li-Cu准晶的x射线旋进衍射图;构造了一个线性相位子场用来解释衍射图与二十面对称性的偏离;用计算机对衍射图进行了模拟,理论结果与实验结果符合得很好;最后指出近准晶结构是处于理想准晶与晶体之间的一种结构,对它的研究将有助于对理想准晶结构的理解。     

An investigation on selective laser melting of Al-Cu-Fe-Cr quasicrystal: From single layer to multilayers

In this study, the effects of processing parameters on the microstructure of Al-Cu-Fe-Cr quasicrystalline (QC) coatings fabricated by selective laser melting (SLM) are investigated. A qualitative analysis on the XRD patterns indicates that the phase composition for the SLM processed coating mainly consisted of Al-Cu-Fe-Cr quasicrystals and α-Al (CuFeCr) solid solution, and with increasing laser energy input or coating thickness, the volume fraction of QC i-Al₉₁Fe₄Cr₅ reduced and those of QC d-Al₆₅Cu₂₀Fe₁₀Cr₅ and crystalline θ-Al₂Cu increased. The formation of cracks during the coating building procedure from single layer to multilayers is also discussed. For the coatings with the same layer number, the pores and balling particles diminish as laser power increases, due to the growth of melting degree. At the early stage of fabrication, with increment of layer number (or coating thickness), pores and balling particles decrease considerably because the molten pool solidified more “slowly”. However, after the layer number increases continuously from 10 to 20, the porosity no longer decreases, and some big size pores, microcracks and fractures appear, especially for the sample obtained at lower laser power. A wavy-like pattern composed chiefly of Al and QC phases, is formed at the interfacial region between substrate and coating due to Marangoni effect.     

引人注目的新材料——准晶材料(二) 准晶基础

描述了准晶的定义,介绍了准晶常用的两种分类方法、三个典型结构模型及准晶结构不完整性等准晶的基础知识。     

大过冷Al-Mn-Si合金的凝固

本文采用玻璃包裹法加热冷却循环处理成分(wt-%)为 Al-25.44Mn-17.15 Si 的三元合金,得到了大过冷度的合金熔体。实验表明,三元合金大过冷凝固时有三次相析出。X 光衍射和透射电镜分析发现,合金中存在着五次对称准晶相及少量的 T 相、α-Al 和 Si 相。     

The nature of dislocation motion in quasicrystals

Calculations in a hydrodynamic model of quasicrystal dynamics show that dislocation motion in these systems is impeded by a drag far greater than that in crystals.     

High-resolution electron microscopy of Al-Mn-Si icosahedral and Al-Mn decagonal quasicrystals

Al-Mn-Si icosahedral and Al-Mn decagonal quasicrystals have been studied by high-resolution electron microscopy. High-resolution micrographs of the Al-Mn-Si icosahedral quasicrystal taken with the incident beam along the five-, three- and two-fold symmetry axes are well interpreted on a three-dimensional Penrose tiling model. An image of the Al-Mn decagonal quasicrystal with the incident beam parallel to the ten-fold symmetry axis shows a pattern of an aperiodic tiling with two types of rhombs which can be distinguished from the Penrose tiling using matching and inflation rules. The Al-Mn decagonal quasicrystal examined coexists coherently with that of icosahedral symmetry exhibiting a definite crystallographic orientation relationship.