By means of first-principles simulations, it was demonstrated that tiny deviations from stoichiometry in the bulk composition of the L10 ordered alloy had a marked effect upon the atomic configuration of the (111) surface. It was predicted that, at 600K, the (111) surface of Ni51Pt49 and Ni50Pt50 alloys corresponded to the (111) truncation of the bulk L10 ordered structure. However, the (111) surface of Ni-deficient Ni49Pt51 was strongly enriched by Pt and was expected to exhibit the pattern of the 2x2 structure. Such a sharp change in the segregation behavior was due to the presence of different antisite defects in the Ni- and Pt-rich alloys and was a manifestation of the so-called off-stoichiometric effect.
Antisite-Defect-Induced Surface Segregation in Ordered NiPt Alloy. L.V.Pourovskii, A.V.Ruban, B.Johansson, I.A.Abrikosov: Physical Review Letters, 2003, 90[2], 026105 (4pp)
Table 11
Diffusivity of 63Ni in Ni-Ti-Cu Alloys
Temperature (K) | Alloy (at%) | D (m2/s) |
1288 | 50.07Ti | 1.2 x 10-14 |
1230 | 50.07Ti | 5.7 x 10-15 |
1144 | 50.07Ti | 1.3 x 10-15 |
1103 | 50.07Ti | 6.8 x 10-16 |
1073 | 50.07Ti | 5.2 x 10-16 |
1023 | 50.07Ti | 2.7 x 10-16 |
933 | 50.07Ti | 4.9 x 10-17 |
783 | 50.07Ti | 7.7 x 10-19 |
998 | 48.83Ti-9.29Cu | 5.7 x 10-15 |
908 | 48.83Ti-9.29Cu | 1.8 x 10-16 |