Investigation of NbC/TiC Heterogeneous Nucleation Interface by First-Principles and Experimental Methods

• Published in: Metals (Basel ) Vol. 9; no. 12; p. 1265
• Main Authors: Dong, Jianhong, Hou, Dejian, Li, Jin-Yan, Huang, Rui
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.12.2019
• Subjects: Atoms & subatomic particles; Carbon; Chemical potential; Chemical precipitation; Covalent bonds; Energy; Epitaxial growth; Experimental methods; Experiments; First principles; High strength low alloy steels; Interface stability; Interfaces; Interfacial properties; Mathematical analysis; Morphology; Niobium carbide; Nucleation; Precipitates; Research methodology; Stacking sequence (composite materials); Steel; Titanium carbide
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met9121265

The mechanism of the heterogeneous nucleation of NbC on TiC precipitates was investigated systematically in this paper. The interfacial properties of NbC (100)/TiC (100), NbC (110)/TiC (110), and NbC (111)/TiC (111) interfaces were studied by first-principles calculations. The results showed that the NbC (111)/TiC (111) interface with the Nb–C bond is the most stable one, and the stability of interfaces with the C–Ti, Nb–Ti, and C–C bonds decreases in turn. The interface of the Nb/C-terminated and Third Layer (TL) stacking sequence (NCTL) has the largest adhesion work (10.15 J/m2) and the smallest equilibrium interface spacing (1.290 Å). In the range of low niobium (Nb) chemical potential and high carbon (C) chemical potential, the nucleation of NbC on TiC precipitates takes precedence over the epitaxy growth in the coherent relationship of [ 1 1 ¯ 0 ] ( 111 ) NbC / / [ 1 1 ¯ 0 ] ( 111 ) TiC , while the nucleation of NbC on TiC precipitates is prior to the epitaxy growth in the coherent relationship of [ 001 ] ( 100 ) NbC / / [ 001 ] ( 100 ) TiC in the range of high niobium (Nb) chemical potential and low carbon (C) chemical potential. Besides, the characteristics of heterogeneous nucleation precipitates in Nb–Ti microalloyed steels were analyzed by transmission electron microscopy (TEM). The orientation relationship between the (Ti, Nb) C and (Nb, Ti) C precipitates follows [ 1 1 ¯ 0 ] ( 111 ) ( Nb ,   TiC ) / / [ 1 1 ¯ 0 ] ( 111 ) ( Ti ,   Nb ) C , which is consistent with the calculated result.