Effect of elastic strain energy on precipitation process of Co81Al5V14 alloy based on microscopic phase field method

The L12 phase volume fraction, size, microstructure significantly influences alloy's important physical and mechanical properties in Co-Al-V superalloy. Based on microscopic phase field method and microelasticity theory, precipitation of ordered L12 phase in Co81Al5V14 alloy were studied. The results indicate that precipitation sequence of Co81Al5V14 alloy is minimally influenced by elastic strain energy and precipitation sequence can be divided into four stages. Elastic strain energy does not significantly affect incubation period of alloy, but it does promote the formation of transitional ordered phase L10 with a single orientation and facilitates precipitation of ordered phase L12. Elastic strain energy causes precipitates to grow and coarsen along specific elastic “soft” direction ([100] and [001]). Elastic strain energy promotes process of ordering and atomic occupancy of the alloy. The effects of elastic strain energy on precipitation mechanism, microstructure and atomic occupancy are discussed in this work, which provides theoretical guidance for the design of Co-Al-V alloys with better properties.