Editorial for the Special Issue on Small-Scale Deformation using Advanced Nanoindentation Techniques

Nanoindentation techniques have been used to reliably characterize mechanical properties at small scales for the past 30 years. Recent developments of these depth-sensing instruments have led to breakthroughs in fracture mechanics, time-dependent deformations, size-dependent plasticity, and viscoelastic behavior of biological materials. This special issue contains 11 papers covering a diverse field of materials deformation behavior. Müller et al. [1] developed a new nanoindentation method to evaluate the influence of hydrogen on the plastic deformation of nickel. Effects of radiation on ferritic-martensitic steels were studied by Roldán et al. [2]. The applications of the depth-sensing indentation method in the mechanical reliability of microelectronic packaging products, such as through-silicon via (TSV) structures and lead-free solder, were performed by Wu et al. [3] and Long et al. [4], respectively. Gan et al. [5] and Chiu et al. [6] investigated the fracture behavior of cementitious cantilever beam and InP single crystals. Studies of nanometer scale deformation of metallic glass materials (Zr-Cu-Ni-Al and La-Co-Al alloys) [7] and Bi₂Se₃ thin films [8] were also part of the collected manuscripts. The mechanical deformation of mammalian cells and other biological materials [9,10] were also discussed in this focus issue. Influence of surface pit on the nanoindentation was studied by Zhang et al. [11]. The editors would like to thank these authors for their contributions to this focus issue.