On the Creep Properties of Nano-particle Reinforced Nickel-matrix Composites of MEMS Microstructures
纳米颗粒增强镍基MEMS器件材料的蠕变性能研究

Structure material of MEMS was combined with nano-oxide particles by synchrotron radiation LIGA microcasting technics. The strength of Al2O3 nano-particle reinforced nickel-matrix composite is 1GPa, which is measured by Microtester with special fixture. Creep rate sensitivity index m of the composite at room temperature was measured by nanoindentation creep test combining the constant loading rate/load and the constant load test. Results show that nano-particle reinforced composite fabricated by LIGA process has high strength; material of MEMS microstructure presents creep behavior at room temperature; the maximum load at indentation depth of 1500nm is independent on loading rate, little viscoelastic and viscoplastic deformation took place during loading process; the indentation creep occurred due to the local high stress underneath the indenter; the average value of m is 0.004, which indicates that Al2O3 nano-particle has effectively reinforced the composite creep-resistating capacity. It is also found that the values of m obtained by different constants P·/P are basically identical, which indicates the insensitivity to loading conditions of this material.