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Huang F.,Chongqing University of Technology | Li M.,Chongqing University of Technology | Ying P.,Chongqing University of Technology | Xu Y.,Chongqing Chuanyi Metallic Functional Materials Co. | Zhang Y.,Chongqing Chuanyi Metallic Functional Materials Co.
Materials Science Forum | Year: 2011

It is well known that the rare-earth elements (RE) have exhibited favorable microalloying effects on the microstructure and properties of silver alloys. In the present investigation, a detailed description of the microstructure of a Silver-4wt.%Copper-0.3wt.% Nickle as-cast alloy containing 0.2wt. % of a cerium element was presented. Particles types occurring and their distribution in the microstructure, as well as the distribution of elements in the phases were described. The result show that the second phase in Ag-Cu-Ni Alloy is Cu-Ni-rich solution phase, some of which forms interdendritic segregation in Ag matrix as eutectic colonies. Trace additions of cerium to the alloy decrease eutectic proportion and size of the Cu-Ni-rich phase, result in finer and more uniform secondary phases distributed in the α-Ag matrix. Besides Cu-Ni-rich phase, the Ni-Cu-Ce-rich and Ag-Cu-Ce-rich phases were found in the alloy. The Ni-Cu-Ce-rich should be the (NiCu)5Ce, which is distributed as dispersive particle in the Ag matrix, and Ag-Cu-Ce-rich phases should be (AgCu)4Ce, which is distributed as fibrous particle of eutectic colonies. Some of (AgCu)4Ce phases are located at the interface between α-Ag matrix and Cu-Ni-rich phases, which indicate that Ce could be segregated at the frontier of Cu-Ni-rich phases during the growth, causing Cu-Ni-rich phase refinement. © (2011) Trans Tech Publications. Source


Huang F.,Chongqing University of Technology | Yin P.,Chongqing University of Technology | Xu Y.,Chongqing Chuanyi Metallic Functional Materials Co. | Zhang Y.,Chongqing Chuanyi Metallic Functional Materials Co.
Advanced Materials Research | Year: 2011

Potentiodynamic electrochemical tests and surface analysis technics, such as scanning electronic microscope (SEM), energy dispersive spectrum (EDS) and X-ray diffraction analysis (XRD), were applied to investigate the microstructure and corrosion behavior of Ag-Cu-Zn-Ni alloys in Na2S solution. The results reveal that the α-Ag phase is the main matrix of the studied silver alloys. The second phase of Ag-4Cu-0.3Ni and Ag-3Cu-Zn-0.3Ni/Ag-6Cu-Zn-0. 3Ni are respectively CuNi and CuNi(Zn) phases. The second phases of Ag-6Cu-Zn-0.3Ni are well-distributed, which leads to an improvement in the corrosion resistance in Na2S solution. © (2011) Trans Tech Publications, Switzerland. Source


Huang F.X.,Chongqing University of Technology | Yin P.,Chongqing University of Technology | Xu Y.H.,Chongqing Chuanyi Metallic Functional Materials Co. | Zhang Y.,Chongqing Chuanyi Metallic Functional Materials Co. | And 2 more authors.
Advanced Materials Research | Year: 2011

The corrosion performance of Ag-Cu-Ni-RE alloys in Na2S has been studied in order to assess the influence of rare earth (lanthanum and cerium) on the Ag-Cu-Ni alloys. Optical microscopy has been used to characterize the microstructures of the samples prior to the electrochemical tests. SEM, EDS and XRD have been used to observe the corrosion morphologies and chemical compositions of the samples. The electrochemical tests has been carried out at room temperature in 0.5, 1and 2% (wt. %) Na2S. The results reveal that the Ag-Cu-Ni-RE alloys exhibit improved corrosion resistance, as well as fine and uniform microstructures. Moreover, surface layers forming on Ag-Cu-Ni-RE alloys exhibit improved protective properties compared to the film growing on the Ag-Cu-Ni alloy. Here, it is also found that when comparing to the dilute Na2S solution conditions, there would be a little decrease of the corrosion rate in 2wt. %Na2S solution. In addition, Ag-Cu-Ni-La-Ce alloy generally exhibits the best corrosion resistance. © (2011) Trans Tech Publications. Source


Yonghong X.,Chongqing University | Yonghong X.,Chongqing Chuanyi Metallic Functional Materials Co. | Hengfei Z.,Chongqing University | Yong W.,Chongqing University | And 2 more authors.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2011

The roles of RE in Ag and Ag alloy were described including purifying melt, refining grain size and improving mechanical properties, wear resistance of electronic contactor and anti-arc properties, increasing oxide resistance, optimizing electrochemical properties as well as improving anti-tarnish ability. The future development and application of Ag alloy containing RE were reviewed and prospected. It was described for series of Ag based electronic contacting materials with RE and functional materials. And then, the application of RE was extended to other precious metal scope, which was beneficial for increasing the add-value of RE element. Source


Wang Y.,Chongqing University | Wang Y.,Chongqing Chuanyi Metallic Functional Materials Co. | Xu Y.,Chongqing University | Xu Y.,Chongqing Chuanyi Metallic Functional Materials Co. | And 2 more authors.
Advanced Materials Research | Year: 2011

In this paper, continuous running test was conducted using the disk drive spindle micromotors used in automobiles DVD. The commutator and brush were made of AuAg/AgCuNiCe/Cu and AgPd/CuNiSn layered composite respectively. In order to investigate the wear behavior of the commutator, the micromotors were dissected after ran continuously for different time. The worn surface of the commutator and the brush were characterized using an SEM equipped with EDS. Also, the cross section of the commutator was analyzed. It was shown that the AuAg layer was not totally worn off until 1500 h of running test. AuAg transferred from the commutator to the brush. It was interesting that Au was found on the silver layer where the depth of wear crater surpassed the thickness of the original AuAg layer. Small particles enriched in Cu, Ni and Ce were observed on the contact surface of AgCuNiCe layer, which was thought to improve the wear resistance of the commutator. The wear mechanism was mainly slight abrasion whereas no effect of arc was found on the sliding contact area. Source

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