Reactive wetting of polycrystalline TiC by molten Zr 55 Cu 30 Al 10 Ni 5 metallic glass alloy
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Hidetoshi Fujii and Kiyoshi Nogi Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047, Japan (Received 23 September 2008; accepted 21 November 2008)
The isotherm wetting and spreading behaviors of polycrystalline TiC by molten Zr55Cu30Al10Ni5 alloy were investigated at 1133 to 1253 K in a vacuum by using a modified sessile drop method. The system displays good wettability with the initial and final stable contact angles of 44 to 50 and 10 to 14 , respectively, mildly depending on the temperature. The spreading kinetics follows well defined exponential functions and could be described by a molecular dynamic model. On the other hand, a ZrC reaction layer was formed at the interface. The wetting was primarily promoted by the Zr adsorption at the triple junction and then by the formation of the reaction layer.
I. INTRODUCTION
Bulk metallic glasses (BMGs) have recently received considerable attention because of their outstanding properties such as high yield strength and good corrosion resistance. However, the catastrophic failure on one dominant shear band after elastic deformation limits their applications.1 To improve their plasticity, great efforts have been devoted to the development of the BMG matrix composites. The second phase in the glass matrix can act as a “crack-stopper” by adding impediments to the shear band propagation, and thus considerable plasticity has been achieved.2 The BMG matrix composites reinforced with fibers or particulates have been prepared by infiltration casting and suction casting,2,3 in which the wettability of the reinforcements by the molten BMG materials plays a key role in their fabrication. However, to the best of our knowledge, only limited work has so far been concerned with the wettability between the BMG alloy and the reinforcement. Jan Schroers et al.4 investigated the wetting and reaction of a Zr41Ti14Cu12Ni10Be23 alloy with W, Ta, Mo, AlN, Al2O3, Si, graphite, and amorphous carbon. They found that Al2O3, Ta, W, Mo, and graphite were well wetted, whereas Si was partially wetted and AlN was poorly wetted. Xu et al.5,6 studied the wetting behavior of polycrystalline a-Al2O3 by a molten Zr55Cu30Al10Ni5 alloy at 1153 to 1273 K and reported the final contact angles approximately 108 , 46 , 20 , and 16 at 1153, 1163, 1193, and 1273 K, respectively. a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2009.0260
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http://journals.cambridge.org
J. Mater. Res., Vol. 24, No. 7, Jul 2009 Downloaded: 16 Mar 2015
In addition, they argued that the spreading progressed through three stages, i.e., incubation, quasi-steady increase, and final equilibrium. Similar work was also performed by Ma et al.7 in the same group. It is worth mentioning that in the aforementioned studies, a conventional sessile drop method, in which the BMG alloy was preplaced on a ceramic or refractory metal surface and the couple was then heated together from room temperature to the desired testing temperature, was used. With such a techniq
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