Effects of Phosphorus and Carbon Contents on Amorphous Forming Ability in Fe-based Amorphous Alloys Used for Thermal Spr
- PDF / 910,902 Bytes
- 8 Pages / 593.972 x 792 pts Page_size
- 5 Downloads / 166 Views
INTRODUCTION
AMORPHOUS alloys have excellent characteristics such as strength, stiffness, magnetism, and corrosion resistance because atoms are aligned like in a liquid. Since amorphous alloys with high amorphous forming abilities were first developed by conventional casting methods in the 1990s, a number of alloys such as La-NiAl,[1] Zr-Al-Cu-Ni,[2,3] Zr-Ti-Cu-Ni-Be,[4,5] Zr-Ti-CuNi,[6] and Cu-Ti-Zr-Ni-Sn-Si[7] alloys have been developed with renewed attention. In particular, Zr-TiCu-Ni-Be[8] alloys show excellent amorphous forming ability (critical cooling rate; about 1 K/s), hardness, strength, stiffness, and corrosion resistance,[5,9] and thus have been used as components of electrical products or sporting goods. However, the manufacturing cost is still high because of the requirement of a vacuum environJEONGHYEON DO, formerly Research Assistant with Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784, Korea, is now Senior Researcher with Advanced Metallic Materials Division, Korea Institute of Materials Science, Changwon 642-831, Korea. SEUNGMUN JUNG and HYUK-JOONG LEE, Research Assistants, BYEONG-JOO LEE and SUNGHAK LEE, Professors, are with Center for Advanced Aerospace Materials, Pohang University of Science and Technology. Contact e-mail: [email protected] GIL-UP CHA, Team Leader, is with Rolling Facilities Group, Pohang Works, POSCO Pohang 790785 Korea. CHANG YONG JO, Director, is with Advanced Metallic Materials Division, Korea Institute of Materials Science. Manuscript submitted July 16, 2012. Article published online February 1, 2013 METALLURGICAL AND MATERIALS TRANSACTIONS A
ment during casting, and the size and shape of the products are limited.[10,11] In addition, amorphous alloys have poor ductility and toughness because the brittle fracture readily occurs due to formation of highly localized shear bands.[12] Thus, if the fabrication method of amorphous/metal coatings, in which the surface consists of an amorphous alloy and the interior substrate consists of a ductile metal having sufficient ductility and fracture toughness, can be developed, this brittle problem can be solved, while fully taking advantages of amorphous alloys. Thermal spraying methods including high velocity oxyfuel (HVOF) use a mixture of oxygen and fuel which is combusted and accelerated through a nozzle. The HVOF process is widely applied in industries because (1) they have very high spray rate and deposition efficiency, (2) they consume fuel gases which are inexpensive and easily obtainable, (3) they require minimum preheating and cooling during spraying, and (4) they are readily applicable to production lines.[13,14] Ferrous amorphous coatings fabricated by the HVOF process have improved the resistance to wear and corrosion[15,16] because of formation of amorphous phases when completely molten ferrous amorphous powders are contacted with a substrate at very fast cooling rates of about 107 K/s.[17] They are cost effective in simultaneously reducing the wear and corrosion on the surf
Data Loading...
