1. School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia
2. CSIRO Manufacturing, P.O. Box 218, 36 Bradfield Road, Lindfield, NSW 2070, Australia
3. State Key Lab of New Ceramics and Fine Processing, School of Materials Science and Engineering, Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China