Correlation of Microstructure and Ballistic Performance of Multilayered Zr-based Amorphous Surface Composites Fabricated
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THE properties required for armor plates are hardness, strength, and fracture toughness, which can improve the mobility of armor vehicles such as tanks and armored vehicles by reducing their weight. However, hard armor plates usually cause poor fracture toughness, weldability, and fabricability, thereby restricting their applications to armor vehicles. Thus, armor plates with high hardness in the surface region and high fracture toughness in the interior region are desired to block or retard the traveling of projectiles. Based on this idea, the multilayered amorphous surface composites are suggested as promising armor materials JEONGHYEON DO and CHANGWOO JEON, Research Assistants, are with the Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784, Korea. DUK-HYUN NAM, Senior Research Engineer, is with the Material Research Team, Hyundai Motors Technical Research Laboratory, Hwasung 445-706, Korea. CHOONGNYUN PAUL KIM, Research Professor, is with Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea. YOUNG BUEM SONG, Senior Researcher, is with the Agency for Defense Development, Daejeon 300-600, Korea. SUNGHAK LEE, Professor, is with the Center for Advanced Aerospace Materials and Department of Materials Science and Engineering, Pohang University of Science and Technology. Contact e-mail: [email protected] Manuscript submitted January 27, 2010. Article published online November 17, 2010 METALLURGICAL AND MATERIALS TRANSACTIONS A
with modified protective capabilities as well as mobility, transportability, maneuverability, maintenance, and corrosion resistance. Recently, remarkable advances in amorphous alloys with high amorphous-forming ability have been made by conventional casting methods.[1–5] Among them, commercialized Zr-based amorphous alloys have excellent amorphous forming ability (critical cooling rate: approximately 1 °C/second; maximum sample diameter: more than 30 mm), hardness, strength, stiffness, wear resistance, and corrosion resistance.[6–11] They can be applied to military purposes, particularly to armor materials requiring excellent ballistic performance,[12–16] because their fracture toughness is higher under dynamic loading conditions than under quasi-static loading conditions.[17–19] Repair and maintenance costs can also be reduced because of their excellent wear and corrosion resistance. Armor materials are generally subjected to dynamic loading conditions, and momentary melting, chemical reactions, and high-temperature oxidation take place by high friction heat in the area ballistically impacted by a projectile.[20,21] Here, adiabatic shear bands can also be formed by the process of thermal-mechanical instability accompanied with severe plastic flow and temperature rise, and cracks occasionally initiate and propagate along the adiabatic shear bands.[22–24] Many complex phenomena including adiabatic shear banding, cracking, falling off, and fracture occur in an extremely short time
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