Fe-B-Nd-Nb metallic glass thin films for microelectromechanical systems

Abstract

In the present study, we investigate the mechanical properties, residual stress, and microprocessing compatibility of Fe67.5B22.5Nd6.3Nb3.7 metallic glass thin films (Fe-MGTFs). The mechanical properties are measured using a specially designed microtensile tester. The fracture toughness of the Fe-MGTF (6.36 MPa × m1/2) is more than twice that of Si, and the highest among the thin films developed for microelectromechanical systems (MEMS) to this point. In addition, the fabrication of freestanding microcantilevers illustrates the low residual stress and high microprocessing compatibility of Fe-MGTFs. The present study verifies the great potential of Fe-MGTFs for use in MEMS.

Flaw-insensitive fracture of a micrometer-sized brittle metallic glass

“…However, toughness values higher than the above small-scale ductile MGs have been measured for brittle but stronger MGs, such as Co-and Fe-based MGs (e.g., in refs. [23,26,27] and the present results). Based on our understanding, such results are only physically justified if fracture at the micrometer-scale is strength-controlled.…”

“…Given that this sample-size effect on fracture occurs at the macroscopic dimensions of millimeters, the work presented here aims at uncovering the size-dependent fracture toughness of MG at the micrometer scale. This has been attempted in earlier studies [23][24][25][26][27][28], with the shortcoming that the toughness was usually reported for only a narrow range of sample sizes, making it an important contribution to assessing the micrometer-scale fracture toughness across a range of sizes with a statistically reliable data set.…”

Current sensors using Fe–B–Nd–Nb magnetic metallic glass micro-cantilevers

“…The fracture toughness and the Young's modulus of the FBNN-MGTF are 6.36 MPa m 1/2 and 79.4 GPa, respectively, which are double and half of the values of the same properties of Si, respectively. The fracture toughness in particular is the highest recorded value among the thin films developed to date for micro-electromechanical systems (MEMS) [8]. The FBNN-MGTF can therefore offer large displacement operation without being destroyed, and is attractive for use in high sensitivity sensors based on mechanical resonance.…”