Effect of Fiber Diameter on Quasi-static and Dynamic Compressive Properties of Zr-Based Amorphous Matrix Composites Rein
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BLE advances in amorphous alloys have been made since amorphous alloys were made by conventional casting methods.[1,2] Particularly in Zr-based amorphous alloys, high amorphous forming ability as well as excellent hardness, stiffness, strength, and corrosion resistance are achieved, and thus these alloys have been applied to high-performance structural components.[3–6] However, they have poor ductility and toughness because the brittle fracture readily occurs by the formation of localized shear bands under tensile or compressive loading conditions. If amorphous matrix composites, in which reinforcements such as fibers or particles are homogeneously dispersed in the amorphous matrix, are developed, problems of poor ductility and toughness can be solved. Fabrication processes of amorphous matrix composites include the partial crystallization of amorphous alloys to disperse nanocrystallines,[7–11] the formation of GYEONG SU KIM, Research Assistant, is with the Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784, Korea. SANG-BOK LEE and SANGKWAN LEE, Senior Researchers, are with the Composite Materials Laboratory, Korea Institute of Materials Science, Changwon 641-010, Korea. HYOUNG SEOP KIM and SUNGHAK LEE, Professors, are with the Center for Advanced Aerospace Materials, Pohang University of Science and Technology, and also with the Material Science and Engineering, Pohang University of Science and Technology. Contact e-mail: [email protected] Manuscript submitted May 14, 2013. Article published online November 14, 2013 1284—VOLUME 45A, MARCH 2014
dendritic crystalline phases from the amorphous melt,[12] and the addition of crystalline particles into the amorphous melt.[13–15] In cases of cast amorphous matrix composites, reactions between reinforcements and amorphous melt should be carefully controlled. In order to effectively fabricate cast composites, it is necessary to develop a new-concept process technology, e.g., a liquid pressing process using a theoretically required minimum loading pressure during the casting.[16,17] It has advantages of complete infiltration of the melt into a fiber perform, elimination of pores formed during solidification, and prevention or minimization of crystallization of amorphous matrix.[18] Most studies on Zr-based amorphous alloys or composites are conducted under static or quasi-static loading, and the deformation behavior under dynamic loading is hardly investigated. The dynamic deformation behavior should be sufficiently clarified so that amorphous alloys or composites can be effectively applied to strategic fields such as defense, aerospace, and, precision machinery.[19] Under dynamic loading such as high-speed metal forming, machining, and ballistic impact, the resistance to deformation or fracture is generally lower than under quasi-static loading because the plastic deformation is often highly localized in a narrow region.[20,21] Qiao et al.[22] reported from the dynamic compressive test of Zr-based amorphous alloys that multiple shear
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