Tuning the mechanical properties of Mo-W alloyed Ni-based multilayered films upon post-annealing at 600?C via modulation of individual layer thickness

Ni-based multilayered film is attractive due to its high good thermal conductivity, oxidation resistance and mechanical properties. However, the influence of individual layer thickness on the microstructure thermal sta-bility and mechanical properties have seldom been investigated. Hence, the 5 at.% Mo and 5 at.% W co-added in Ni/NiAl multilayers with individual layer thicknesses ranging from 10 nm to 160 nm were synthesized using co -sputtering. Upon post-annealing at 600 degrees C, the phase separation of gamma-Ni solid solution in multilayer occurs, precipitating dispersed nano-sized alpha-W phases in major when individual layer thicknesses are lower than 40 nm. The periodical layer interfaces of these multilayers are maintained with excellent thermal stability. The hardness of multilayer is enhanced with reduction of individual layer thicknesses due to grain boundary relaxation, increased layer interfacial barriers and W-related precipitations as obstruction for dislocations movement, showing anneal hardening significantly. Due to crack deflection at the layer interfaces, less brittle W-relative phase precipitation and bare columnar crystals growth, the superior toughness is achieved for 600 degrees C annealed multilayer with individual layer thicknesses of 40 nm. Therefore, 5 at.% MoW co-alloyed Ni-based multilayer are suitable for high-temperature applications with excellent mechanical properties by modulation of individual layer thicknesses.

Automated summary

Ni-based multilayered film with 5 at.% Mo and 5 at.% W content has been synthesized. The individual layer thickness was modulated from 10 nm to 160 nm. The multilayer exhibited excellent thermal stability and improved hardness with reduced individual layer thickness. The 40 nm individual layer thickness resulted in superior toughness due to crack deflection and less brittle phase precipitation.