Influence of heat-resistant coatings on the structure of alloys ZhS6K

Conclusions

• 1. Diffusion of the elements of heat-resistant coating based on nickel monoaluminide with additions of Cr, W, Si, C into the nickel alloy ZhS6K causes a substantial change of its composition and structure at a considerable depth: after facing at 1200°C 10 min up to 35–50 μm, after additional holding at 1100°C 160 and 500 h to 250–350 and 400–500 μm, respectively.

• 2. Additional holding at 1100°C and diffusion of elements of the coating into the alloy are factors impairing the composition and structure of the protected alloy. Additional holding leads to the segregation of acicular secondary phases throughout the bulk of the alloy (the volume fraction is 2.5% beyond the diffusion zone). Diffusion of elements of the coating into the alloy intensifies the segregation of secondary phases(near the coating their volume fraction increases to 7.5%).

• 3. Silicon that diffused from the coating into the alloy does not concentrate in the matrix of the alloy where its mass fraction remains almost unchanged (0.25–0.4%) but in the acicular phase in which, after additional holding at 1100°C 160 and 500 h, the mass fraction of Si near the coating attains 2.0 and 3.2%, respectively.