Stability and crystal structures of iron carbides: A comparison between the semi-empirical modified embedded atom method and quantum-mechanical DFT calculations

Structure and stability of hcp iron carbide precipitates: A first-principles study

“…The calculations show that for the fcc-Fe based model (a), the formation energies are very high (above 100 meV/atom) for all C concentrations. For example, for Fe 4 C the calculated formation energy is about 116 meV/atom, which is higher than that of γ'- Fe 4 C (about 94 meV/atom) using the same method [41] . Fig.…”

“…The coordination in ε'-Fe 2 C is very similar to those in η-Fe 2 C as shown in Table 2 . Therefore, it is expected that these two phases of iron carbide have a very similar bonding [ 40 , 41 ].…”

“…(Å) Δ E f (meV/atom) References ε-Fe 2 C Jack-1 a 1 = a o c 1 = c o a o = 2.834 c o = 4.1673 +120.4 [ 21 , 22 ] Jack-2 a 2 = √3a o c 2 = c o a o = 2.773 c o = 4.295 +35.3 [ 21 , 22 ] Jack-3 a 3 = 2√3 a o c 3 = c o a o = 2.771 c o = 4.291 +27.9 [ 21 , 22 ] ε'-Fe 2 C hcp a' = 2 a o c' = c o a o = 2.744 c o = 4.267 +26.7 present work η-Fe 2 C Orth. a η = 4.707 b η = 4.280 c η = 2.824 +17.3 [ 21 , 41 ] θ-Fe 3 C Orth. a θ = 5.037 b θ = 6.720 c θ = 4.482 +20.6 [ 21 , …”

“… a η = 4.707 b η = 4.280 c η = 2.824 +17.3 [ 21 , 41 ] θ-Fe 3 C Orth. a θ = 5.037 b θ = 6.720 c θ = 4.482 +20.6 [ 21 , 41 ] ε-Fe Hcp a 0 = 2.523 c 0 = 4.375 +194.7 present work Fe ordering ε'-Fe 2 C (hcp) Fe series: ABABAB a' = 2 a o c' = c o a o = 2.865 * c o = 4.020 +52.4 Present work h- Fe 2 C Fe series: ABCBAB a' = 2 a o c' = c o a 0 = 2.704 c 0 = 4.342 +62.5 Present work h- Fe 2 C Fe series: ABCBAC a' = 2 a o c' = c o a 0 = 2.660 c 0 = 4.377 +162.0 Present work …”

Structural, elastic, and thermal properties of cementite (Fe3C) calculated using a modified embedded atom method

“…1 and 3. One of the commonly used 2NN MEAM potentials for the Fe-C system developed by Byeong-Joo Lee 4 is designed to predict the interactions of interstitial C atoms with defects, such as vacancies. According to Fang et al, 5 Lee's potential predicts that cementite is only stable up to a temperature of 750 K. 5 Experimentally, however, cementite is metastable with a positive heat of formation 6 and only decomposes between 1100 and 1200 K. 7,8 Among recent interatomic potentials [8][9][10][11][12] for the Fe-C system, EAM potentials by Lau et al 10 and Ruda et al 12 and the short ranged Tersoff-Brenner type analytical bond order potential (ABOP) by Henriksson et al 8 all promise to predict properties of cementite reasonably well. In the potentials by Lau et al 10 and Ruda et al, 12 however, the single element potential for C does not predict properties of both graphite and diamond well.…”