【作者】 石鑫；

【导师】 蒋敏；

【作者基本信息】 东北大学 ， 材料学， 2018， 硕士

【摘要】 Au-Cu-Pd三元合金在纳米催化领域和作为牙科医用材料与钎焊材料具有重要应用,其三元合金相图在合金研究和开发中有着重要的指导作用。然而由于贵金属合金研究成本高,截至目前对该体系的研究还十分薄弱。因此对Au-Cu-Pd三元系合金的相平衡研究是十分必要的。本工作采用相平衡测定的扩散偶法,将Au46Cu46Pd8/Au3Pd,Au46Cu46Pd8/AuPd3两个扩散偶试样在350℃下进行平衡扩散处理,应用扫描电子显微镜(SEM)观察扩散偶的组织形貌,能谱分析仪(EDS)和电子探针微区成分分析(EPMA)确定扩散层成分、建立各元素成分分布曲线、分析扩散路径,以此对富有争议的Au-Cu-Pd三元合金350℃下等温截面富Au一侧和Au-Pd区域的相平衡进行完善和补充。本工作还使用X射线衍射仪(XRD)和透射电子显微镜(TEM)对Au3Pd、AuPd3和Au46Cu46Pd8三个特殊成分合金进行了结构分析,并使用差示扫描量热法(DSC)测定了 Au46Cu46Pd8合金的有序-无序转变温度。实验发现,Au3Pd、AuPd3和Au46Cu46Pd8均为单相结构,其中Au46Cu46Pd8处于AuCu L10型有序结构相区内,它的有序-无序转变温度为506.2℃。Au3Pd和AuPd3均处于fcc_A1无序相内。Au46Cu46Pd8/Au3Pd和Au46Cu46Pd8/AuPd3两扩散偶试样均形成一个扩散层组织。其中Au46Cu46Pd8/Au3Pd试样的扩散层被确定为Au3Cu L12型有序相,而Au46Cu46Pd8/AuPd3扩散偶中形成的三元固溶体相尚未有研究报道,暂命名为X相。根据扩散偶扩散区各元素的成分分布曲线确定了该扩散路径上单相区的成分范围,以及两相区的共轭线。本工作对Au-Cu-Pd三元合金350℃下等温截面图富Au部分和Au-Pd一侧的相平衡进行了修正,获得了更加科学准确的相图信息。更多还原

【Abstract】 As the Au-Cu-Pd ternary alloy is of vital applications in nanocatalysis and as a kind of dental material and a brazing material,its phase diagram plays an important guiding role in the research and development of alloys.However,due to the high research cost of precious metal alloys,the study of this system so far is still very weak.Therefore,it is necessary to study on the phase equilibria of the Au-Cu-Pd ternary alloys.In this work,a diffusion-coupled method was used for phase equilibrium measurement;two diffusion-coupled Au46Cu46Pd8/Au3Pd and Au46Cu46Pd8/AuPd3 samples were subjected to equilibrium diffusion treatment at 350℃.Scanning Electron Microscopy(SEM)was used to observe the morphology of the diffusion couple.The Energy Dispersive Spectrometer(EDS)and the Electron Probe Micro-Analyzer(EPMA)were used to determine the compositions of the diffusion layers,plot the distribution curve of the elemental components,and to analyze on the diffusion paths so that there are supplements of the phase equilibria at the rich-Au side and the Au-Pd region of the controversial Au-Cu-Pd ternary alloy phase diagram at the isothermal section of 350℃.X-ray Diffractometer(XRD)and Transmission Electron Microscopy(TEM)were also used in this work to analyze the structure of Au3Pd,AuPd3 and Au46Cu46Pd8,which are three special alloys in this system.The Differential Scanning Calorimetiy(DSC)was used to determine the order-disorder transition temperature of the Au46Cu46Pd8 alloy.The experimental results show that Au3Pd,AuPd3 and Au46Cu46Pd8 are all single-phase structures.Au46Cu46Pd8 is in the region of AuCu L10 ordered-structure phase,whose orderdisorder transition temperature is 506.2 ℃ and both Au3Pd and AuPd3 are in the fcc_Al disordered phase.Both Au46Cu46Pd8/Au3Pd and Au46Cu46Pd8/AuPd3 samples have only one diffusion layer.The diffusion layer of the Au46Cu46Pd8/Au3Pd sample was identified as the Au3Cu L12-type ordered phase,while the ternary solid solution phase formed in the Au46Cu46Pd8/AuPd3 diffusion couple has not been reported yet,and is tentatively named as the X phase.The composition range of the single-phase region on the diffusion path and the conjugate line of the two-phase region were determined according to the composition distribution curve of each element of the diffuse diffusion regions.In this work,the rich-Au side and the Au-Pd region of the Au-Cu-Pd ternary alloy at the isothermal section of 350℃was modified,so that pieces of information on a more scientific and accurate phase diagram were thereby obtained.更多还原