Abstract:

The precipitation of the L12 ordered intermetallic phase γ′ from the co-lattice non-ordered face-center cubic parent phase γ during the ageing process of the CoAlW alloys was simulated using the phase field simulation technique. The chemical free energy surfaces of the concentration and the ordered degree were constructed based on the description of the structure ordered degree by the form of static concentration wave. The strain of crystal lattice caused by mispairing and 4 antiphases of the L12 structure were introduced into the model, and the effect of the difference of the modules of elasticity of 2 phases on the microstructure evolution was taken into account. The microstructure in accordance with the experiment was obtained by a 2-dimensional computer simulation, proving the γ/γ′-type precipitation hardening mechanism in the CoAlW alloys.

Key words: metallic materials, CoAlW alloy, phase field simulation,  , γ/γ′-type precipitation hardening, microstructure evolution