Heterogeneous interface-enhanced strength of Ni/Ni-W laminated nanocomposites for high-temperature MEMS devices

The application of LIGA Ni and nanocrystalline binary Ni-X(X = W, Mo, Fe) alloys in the micro-electromechanical systems is severely limited due to their strength and ductility trade-off at elevated temperatures. Aiming at such a problem, here we designed Ni/Ni-W laminated nanocomposites with heterogeneous interfaces, and investigated their mechanical behavior at 400 degrees C. We found that the strength of the laminated nanocomposites with different thickness ratios of Ni layers to Ni-W layers at 400 degrees C could reach 400-620 MPa, being two to three times larger than that of traditional LIGA Ni, and their elongation to failure is above or equal to 10%. Introduced heterogeneous interfaces greatly improved the high-temperature tensile properties through the transition of the grain growth direction in the Ni layers from deposition direction to the loading direction and the geometrically constrained premature failure of relaxed Ni-W layers. These findings can offer a potential opportunity to apply the heterogeneous nanocomposites in the field of high-temperature micro-electro-mechanical system devices.

Automated summary

In this study, Ni/Ni-W laminated nanocomposites with heterogeneous interfaces were designed and exhibited higher strength and elongation at high temperatures. The introduction of heterogeneous interfaces significantly improved the mechanical properties at high temperatures through changes in grain growth direction and constrained failure of relaxed layers.