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Journal of Alloys and Compounds - Article in Press, Accepted Manuscript Ti microalloying effect on corrosion resistance and thermal stability of CuZr-based bulk metallic glasses X.P. Niea, X.H. Yangb and J.Z. Jianga aInternational Center for New-Structured Materials (ICNSM), Zhejiang University and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, PR China bJinhua college of Profession and Technology, Jinhua, Zhejiang, 321007, PR China Received 19 December 2008; revised 3 March 2009; accepted 4 March 2009. Available online 17 March 2009. Abstract Bulk metallic glasses (BMGs) of (Cu37.6 Zr46Ag8.4Al8)100-xTix with x = 0, 1, 2 and 4 at.% were prepared by copper mold casting. The corrosion resistance of the CuZr-based BMGs with different Ti contents was carefully examined by potentiodynamic polarization tests in 1 N NaOH, 1 N H2SO4, 1 N H2SO4 + 0.01 N NaCl and 1 N H2SO4 + 0.1 N NaCl solutions, respectively. The BMGs exhibit excellent corrosion resistance in 1 N NaOH and 1 N H2SO4 solutions. Ti addition greatly improves the newly-developed BMGs’ corrosion resistance in both H+ and Cl- ions containing solutions. The influence of Ti addition on glass forming ability (GFA) and thermal stability was investigated by x-ray diffraction and differential scanning calorimetry. It is found that the alloys still have large GFA although thermal stability is slightly deteriorated with Ti addition. Intermetallics - Article in Press, Corrected Proof Golden Mean analysis of bulk metallic glasses with critical diameter over half-inch for their mole fractions of compositions A. Takeuchia, A.R. Yavaria, b and A. Inouea aWPI Research Center, Tohoku University, Sendai 980-8577, Japan bEuronano, LTPCM-CNRS, Institut National Polytechnique de Grenoble, BP 75, 38402, St-Martin-d'Hères Campus, France Received 12 June 2008; revised 29 November 2008; accepted 12 February 2009. Available online 18 March 2009. Abstract Eighteen bulk metallic glasses (BMGs) with critical diameters over 15 mm in Pd-, Zr-, Mg-, Y-, La-, Pt- and Ca-based multicomponent alloys were analyzed for their mole fractions of compositions with Golden Mean ( 1.618). The results proved that the 18 BMG compositions are describable with m−n or mΦ−n where Φ−n is −(n+1) plus −(n−1) and m and n are positive integers. The maximum difference in fractions between the analyzed and experimental compositions was 0.038. The irrational nature of makes the compositions of the 18 BMGs different from those of the stoichiometric intermetallic compounds and near eutectic compositions, leading to the high glass-forming ability. The possible prototypes of the 18 BMGs have the ability to form critically-percolated local atomic arrangements for both Metal–Metal and Metal–Metalloid types of BMGs. Golden Mean analysis provides a new alloy design for fractions of alloying elements owing to its irrationality. Appl. Phys. Lett. 94, 112507 (2009) Weak exchange effect and large refrigerant capacity in a bulk metallic glass Gd0.32Tb0.26Co0.20Al0.22 Yongsheng Liu,1 Jincang Zhang,2 Youquan Wang,3 Yanyan Zhu,1 Zhenglong Yang,4 Jing Chen,1 and Shixun Cao2 1Department of Mathematics and Physics, Shanghai University of Electric Power, Shanghai 200090, People's Republic of China 2Department of Physics, Shanghai University, Shanghai 200444, People's Republic of China 3Department of Materials Science and Engineering, Shanghai University, Shanghai 200072, People's Republic of China 4Institute of Functional Polymer Materials, Tongji University, Shanghai 200092, People's Republic of China The magnetic behavior and refrigeration capacity of Gd0.32Tb0.26Co0.20Al0.22, a bulk metallic glass (BMG) fabricated by a copper-mold suck-casting method, are investigated. The Curie temperature increases from 79 K at 200 Oe to 95 K at 50 000 Oe. A weak exchange field of 25 T in the BMG system, caused by the strong disorder, is derived by the mean-field approximation. The maximum magnetic entropy change (8.02 J kg−1 K−1) and the refrigerant capacity (642 J kg−1) for 5 T indicate the BMG has the better refrigerant efficiency compared to known magnetic refrigerants. ©2009 American Institute of Physics Journal of Alloys and Compounds - Article in Press, Accepted Manuscript Investigation of Precipitation Phases in As-cast Wedge Ingot of Bulk Amorphous Zr56.6Cu17.3Ni12.5Al9.6Ti4 Alloy Dawei Xinga, Jun Shena, lunyong Zhanga, Jianfei Suna, Xiaodong Wanga, Huan Wanga, Yongjiang Huanga and Peter K. Liawb aMaterials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China bMaterials Science and Engineering, the University of Tennessee, Knoxville, TN, 37996, USA Received 16 October 2008; revised 3 March 2009; accepted 3 March 2009. Available online 17 March 2009. Abstract In order to clarify the competing relationships among the intermetallic precipitation phases during the cooling of a bulk amorphous Zr56.6Cu17.3Ni12.5Al9.6Ti4 alloy, the wedge shaped ingots of this alloy were made by casting the melt into a wedge-shaped copper mould, and then the zones with different cross sections were studied by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that these phases are very different in both the morphology and sizes, and they are dependent on the thickness of wedge ingot, i.e., the cooling rates. It is therefore concluded that the Zr2Ni phase is the strongest competing rival to the amorphous matrix in this alloy. These findings support that compared to Zr-Ni pair, Zr-Cu pair has a larger glass forming tendency. The glass forming ability can be improved by inhibiting the precipitation of Zr2Ni phase by, for example, decreasing the Ni content in this alloy. [ Last edited by hslining on 2009-9-21 at 23:27 ] |
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