• PDF / 1,153,119 Bytes
• 13 Pages / 584.957 x 782.986 pts Page_size
• 73 Downloads / 232 Views

DOWNLOAD

REPORT

---

Ping Li, Jin Yu, Lili Wang, Farhad Saba, and Ge Dai Jiangsu Key Lab for Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China

Siyuan He School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China (Received 26 August 2016; accepted 4 January 2017)

We present a novel route to fabricate 3D nanoporous a-Ti foams by dealloying of TiCu master alloy in solid state using Mg powders. Pure open-cell nanoporous a-Ti foams are fabricated with BET surface area of 34.4 6 0.8 m2/g and pore size in the range of 2–50 nm. The dealloying using powders is a solid state chemical reaction process to form Cu2Mg phase and Ti/Mg nanocomposites. The constituent of Cu in the TiCu alloy was dissolved into Mg powders thanks to the kinetics of interface reaction and volume diffusion. The pore-forming mechanism is a solid-state interdiffusion process. The ligament coarsening is from 492 to 650 nm with increasing of the dealloying temperature. The hardness and elastic modulus in nanoporous a-Ti foam follow linear decay fit with ligament size increasing. Our results demonstrate a facile strategy for the fabrication of nanoporous Ti foams with novel nanostructures and tailored properties.

I. INTRODUCTION

Nanoporous metal foams represent the ultimate form factor of metal and have attracted much more attention for their unique mechanical properties and excellent functional properties.1–3 These materials, characterized by nanoporous structures and high specific surface area, have been considered in electrode, catalyst, sensors, actuators, and filtration applications.4,5 Synthetic strategies for preparing nanoporous foams are dealloying,6 templating,7 laser etching,8 and combustion synthesis.9 Most researches presently conducted using dealloying techniques in an aqueous solution.6,10 In this method, one or more base constituents of an alloy are removed by selective corrosion in an acid or alkaline solution, resulting in the formation of noble nanoporous metals with fine and homogeneous structures. This method is most effective for preparing relatively noble nanoporous metals such as those of Au,10 Pt,11 Pd,12 Cu,13 and Ni14 and so on. Titanium (Ti) is an attractive material with excellent mechanical properties, corrosion resistance, and biocompatibility.15 Therefore, nanoporous Ti may provide new functional applications using as filters for gases or fluids, Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2017.19

media for gas storage or adsorption, gas sensing, and biomaterials.16,17 However, titanium and titanium alloys can’t generate nanoporous structures by the normal dealloying method because of their low standard electrode potential. The dealloying based on corrosion phenomenon lead to either the formation of titanium oxide or selective dissolution of Ti.18,19 Recently, Wada et al.16 developed a dealloying method using magnesium (Mg) melt instead of aqueous solution. They