Segregation-induced phase transformations in grain boundaries

Structural phase transformations in metallic grain boundaries.

Structural transformations at interfaces are of profound fundamental interest as complex examples of phase transitions in low-dimensional systems. Despite decades of extensive research, no compelling evidence exists for structural transformations in high-angle grain boundaries in elemental systems. Here we show that the critical impediment to observations of such phase transformations in atomis...

Effect of interface phase transformations on diffusion and segregation in high-angle grain boundaries.

Recent experimental measurements of Ag impurity diffusion in the Σ5(310) grain boundary (GB) in Cu revealed an unusual non-Arrhenius behavior suggestive of a possible structural transformation Divinski et al., [Phys. Rev. B 85, 144104 (2012)]. On the other hand, atomistic computer simulations have recently discovered phase transformations in high-angle GBs in metals Frolov et al., [Nat. Commun....

Segregation and structural transformations at R = 3 grain boundaries in NiAl: A Monte-Carlo study

Grain boundary structure and grain boundary segregation in stoichiometric and Ni-rich compositions of NiAl are studied by molecular statics and grand-canonical Monte-Carlo simulations in conjunction with an embedded-atom potential. Significant Ni segregation is found at the R = 3(1 1 1) and R = 3(2 1 1) grain boundaries, with segregation isotherms showing a saturation effect. The amount of Ni s...

Segregation of Interstitial Impurities at Grain Boundaries in Transition Metals

SEGREGATION AT SPECIAL GRAIN BOUNDARIES IN Fe-Si ALLOY BICRYSTALS

The segre ation of silicon to the C=3, 112) and C=S, (013) symmetrical grain boundaries 1 was studied in well-fefined bicrystals of an Fe-l .9 at%Si alloy annealed in the range 773 1173 K using Auger electron spectroscopy. The segregation enthal y, AI1 = -8.1 * 0.5 kJ/mol, and entropy, AS = -69 r 0.4 i/(mol K), were determined for the (013f grain boundary in the temperature range 973 1173 K. Fo...