| Title |
Effect of Temperature-Dependent Phase-Selective Nitriding on Hardness and Wear Resistance of FCC Dual-Phase Fe-Mn-Cu-Al Alloy |
| Authors |
강규병(Gyu Byeong Kang) ; 조영찬(Young Chan Cho) ; 백민아(Min Ah Baek) ; 하태준(Taejun Ha) ; 김동회(Dong Hoe Kim) ; 나태욱(Taewook Na) |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.8.691 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Dual-phase alloy; Selective nitriding; Diffusion kinetics; Surface hardening; Wear resistance |
| Abstract |
Temperature-dependent phase-selective nitriding was applied to a face-centered cubic (FCC) dual-phase Fe-Mn-Cu-Al alloy to investigate the correlation between microstructural evolution, diffusion kinetics, and surface mechanical performance. The alloy exhibited distinct phase separation into Fe-rich and Cu-rich regions caused by metastable liquid phase separation during solidification, resulting in a heterogeneous chemical distribution and mechanical response. Gas nitriding treatments were conducted at 700, 800, and 900 °C for 1-2 h under an NH3 (9.85%) + N2 balance atmosphere, with controlled H2 addition to regulate the nitrogen potential and suppress excessive surface film formation. Microstructural characterization using optical microscopy, SEM/EDS, XRD, and GDS demonstrated that the nitriding behavior depended strongly on both temperature and phase constitution. Nitrogen preferentially diffused into the Fe-rich domains to form internal nitride precipitates, whereas the Cu-rich regions exhibited limited nitriding due to their lower nitrogen solubility and slower diffusion rates. The nitrided layer thickness increased with temperature and holding time, reaching a maximum depth of approximately 60 μm at 800 °C for 2 h. Micro-Vickers hardness measurements revealed a significant increase in surface hardness from 250 HV in the as-cast condition to 909 HV under the optimal nitriding condition. Pin-on-disc wear testing showed a pronounced reduction in weight loss and wear track width, confirming improved wear resistance. These findings indicate that diffusion-controlled phase-selective nitriding provides an effective strategy for enhancing surface durability while maintaining bulk structural integrity in dual-phase Fe-Mn-Cu-Al alloys. |