Plasma-Assisted Surface Modification of Two-Phase Intermetallic Alloy Composed of Ni 3 X Type Structures
- PDF / 671,862 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 36 Downloads / 146 Views
1128-U05-32
Plasma-Assisted Surface Modification of Two-Phase Intermetallic Alloy Composed of Ni3X Type Structures Y. Kaneno1, N. Matsumoto1, N. Tsuji2, S. Tanaka3 and T. Takasugi1 1 Department of Materials Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan 2 Tanaka Ltd., 1-10-6 Tedukayama-naka, Sumiyoshiku, Osaka 558-0053, Japan 3 SDC Inc., 4-132-1 Kannabe-cho, Sakai-ku, Sakai, 590-0984, Japan
ABSTRACT A two-phase intermetallic alloy composed of Ni3Al (L12) and Ni3V (D022) was plasmanitrided or -carburized in dependence of temperature and time. It was found that the hardness of the surface layer of the present intermetallic alloy was enhanced by both plasma-nitriding (PN) and -carburizing (PC), and primarily depended on treating temperature; the maximum surface hardness of the alloy was shown by nitriding at around 850 K and by carburizing at 1025 K. In addition, the hardened layers due to PN and PC effectively kept their hardness up to a high temperature. The XRD analysis revealed that vanadium nitride (VN) and vanadium carbide (VC) were formed in the surface of the nitrided and carburized alloy, respectively, suggesting that the enhanced surface hardness was attributed to the dispersion hardening due to the nitrides and carbides.
INTRODUCTION Recently, the present authors have succeeded in developing a new type of two-phase intermetallic alloys composed of Ni3Al (L12) and Ni3V (D022) phases [1, 2]. The microstructure is composed of Ni3Al and Ni solid solution (A1) phases at high temperatures, and the Ni solid solution phase is decomposed into Ni3Al + Ni3V by a eutectoid reaction at a low temperature. The two-phase microstructure is thus comprised of only intermetallic (ordered) phases with high structural coherency, leading to a high microstructural stability at high temperatures. The twophase intermetallic alloys have been found to exhibit excellent mechanical and creep properties especially at high temperatures due to their stable microstructures [3], and thereby are expected to be used as high-temperature structural materials such as jet engine and gas turbine parts. However, wear resistance property of the present intermetallic alloys is insufficient for application of conventional heat-resistant elements because hardness is not so high. Therefore, surface modification to improve tribological property of the present intermetallic alloys is desired. Some studies on nitriding and carburizing of nickel based alloys including superalloys have been reported [4-6]. However, whether or not nitriding and carburizing are useful in surface modification of the intermetallic alloys including the present multi-phase intermetallic alloys is unknown. In this study, the capability of the surface hardening by means of plasma-nitriding and -carburizing has been investigated in dependence of temperature and time. The alloy contained Nb, Co and Cr to enhance hardness or to improve oxidation resistance.
EXPERIMENT The nominal composition of the material used in this study was Ni70.5A
Data Loading...
