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Micro-Fracture testing of Ni-W Microbeams Produced by Electrodeposition and FIB Machining

Published online by Cambridge University Press:  26 February 2011

David Armstrong ,
Abdul Haseeb ,
Angus Wilkinson  and
Steve Roberts
David Armstrong
Affiliation:
david.armstrong@materials.ox.ac.uk, University Of Oxford, Materials Department, Parks Road, oxford, OX1 3PH, United Kingdom, 01865273768
Abdul Haseeb
Affiliation:
haseeb@mme.buet.ac.bd, Bangladesh University of Engineering and technology, Dhaka, N/A, Bangladesh
Angus Wilkinson
Affiliation:
angus.wilkinson@materials.ox.ac.uk, Oxford University, Materials Department, Parks Road, Oxford, OX1 3PH, United Kingdom
Steve Roberts
Affiliation:
steve.roberts@materials.ox.ac.uk, Oxford University, Materials Department, Parks Road, Oxford, OX1 3PH, United Kingdom
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Abstract

Electrodeposited nickel-tungsten alloys are being considered as a candidate material for components for microelectromechanical systems (MEMS) fabricated by the LIGA (German acronym for lithography, electrodeposition, and forming) technology. In spite of having a useful range of properties including; hardness and strength, better tribological and chemical resistance and improved high temperature resistance as compared with the conventionally used electrodeposited Ni, these alloys possess certain brittleness. In this study, the fracture toughness of Ni-17.5 at%W alloy microcantilever beams (dimension: 60µm × 20µm x 14µm) fabricated by UV lithography and electrodeposition and notched by focused ion beam machining is investigated. Load was applied to the beams using a nanoindenter, which also allowed accurate positioning of the sample. Fracture toughness was calculated from the fracture load assuming a linear elastic behaviour. The Ni-W alloy beams were found to possess a mean fracture toughness of 2.97 MPa √m. The fracture toughness of Ni-W alloy is found to be higher than that of Si - another important MEMS material, but considerably lower than that of electrodeposited nickel and nickel base alloys.

Keywords

fracturemicroelectro-mechanical (MEMS)ion-beam processing
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 983: Symposium LL – Focused Ion Beams for Analysis and Processing , 2006 , 0983-LL08-07
Copyright
Copyright © Materials Research Society 2007

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