Multi-scale modelling of Suzuki segregation in gamma' precipitates in Ni and Co-base superalloys

Srimannarayana, P and Vamsi, KV and Karthikeyan, S (2015) Multi-scale modelling of Suzuki segregation in gamma' precipitates in Ni and Co-base superalloys. In: 2nd European Symposium on Superalloys and their Applications, MAY 12-16, 2014, Giens, FRANCE.

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Abstract

The high temperature strength of alloys with (gamma +gamma') microstructure is primarily due to the resistance of the ordered precipitate to cutting by matrix dislocations. Such shearing requires higher stresses since it involves the creation of a planar fault. Planar fault energy is known to be dependent on composition. This implies that the composition on the fault may be different from that in the bulk for energetic reasons. Such segregation (or desegregation) of specific alloying elements to the fault may result in Suzuki strengthening which has not been explored extensively in these systems. In this work, segregation (or desegregation) of alloying elements to planar faults was studied computationally in Ni-3(Al, Ti) and Co-3(W, Al) type gamma' precipitates. The composition dependence of APB energy and heat of mixing were evaluated from first principle electronic structure calculations. A phase field model incorporating the first principles results, was used to simulate the motion of an extended superdislocation under stress concurrently with composition evolution. Results reveal that in both systems, significant (de) segregation occurs on equilibration. On application of stress, solutes were dragged along with the APB in some cases. Additionally, it was also noted the velocity of the superdislocation under an applied stress is strongly dependent on atomic mobility (i. e. diffusivity).

Item Type:	Conference Proceedings
Series.:	MATEC Web of Conferences
Publisher:	E D P SCIENCES
Additional Information:	Copy right for this article belongs to the E D P SCIENCES, 17 AVE DU HOGGAR PARC D ACTIVITES COUTABOEUF BP 112, F-91944 CEDEX A, FRANCE
Keywords:	PHASE-FIELD SIMULATION; DISLOCATIONS; ALLOYS; NI3AL; DEFORMATION; TEMPERATURE; EVOLUTION; ENERGIES; CRYSTALS; DEFECTS
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	29 Apr 2015 05:56
Last Modified:	29 Apr 2015 05:56
URI:	http://eprints.iisc.ac.in/id/eprint/51462

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