Study On The Preparation And Properties Of Nanoporous Ag-based And Cu-Sn Alloys By Dealloying Of Ternary Alloys

In this thesis, rapidly solidified Al-Ag-Ni/Ru/Fe precursor alloys were dealloyed in a20wt.%NaOH solution to investigate the nano-alloying of immiscible systems (Ag-Ni, Ag-Ru and Ag-Fe) induced by dealloying. Various Ag-based nanoporous alloys were fabricated. In addition, three rapidly solidified Mg-Cu-Sn precursor alloys were also dealloyed in a1wt.%tartaric acid to fabricated Cu-Sn alloys. Li-ion battery discharge/charge tests of as-dealloyed nanoporous CugSn5were carried out to investigate its potential application as anode materials of Li-ion batteries.X-ray diffraction (XRD), combined with binary equilibrium phase diagram was used to study the rapidly solidified Al-Ag-Ni/Ru/Fe precursor alloy ribbons. The results revealed that the Al-Ag-Ni/Ru/Fe precursor alloys consist of single Al(Ag,Ni), Al(Ag,Ru) and Al(Ag,Fe) phases respectively, in which Ag and Ni, Ag and Ru, Ag and Fe form solid solutions with Al. The as-dealloyed Al-Ag-Ni and Al-Ag-Ru precursor alloys were observed and analyzed through XRD, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX). transmission electron microscopy (TEM), and high resolution TEM (HRTEM) with nano-beam energy dispersive X-ray analysis (NB-EDX). The results showed that Ag and Ni, as well as Ag and Ru, has formed Ag(Ni) and Ag(Ru) solid solutions. It indicates that the nano-alloying of immiscible systems induced by dealloying of ternary alloys is feasible. After heat treatment, Ag(Ru) solid solution dealloyed and formed nanoporous Ag-RuO2nanocomposites. Nanoporous Ag-RuO2nanocomposites show good supercapacity property and can be potential electrode materials in supercapacity. The NPS/Fe3O4nanocomposites were obtained by chemically dealloying of rapidly solidified Al-Ag-Fe precursor alloys in a20wt.%NaOH solution. In the nanocomposites, the NPS matrix exhibits an open bicontinuous interpenetrating ligament-channel structure with ligament/channel sizes of20～50nm, and the embedded Fe3O4particles are octahedral and several hundred nanometers in size. Through changing the Ag/Fe atomic ratio in the Al-Ag-Fe precursors, we can tune the magnetic properties of the NPS/Fe3O4nanocomposites. Antibacterial tests demonstrate that the NPS/Fe3O4nanocomposites show excellent antibacterial activities against E. Coli K12, and the embedded Fe3O4makes these materials magnetically recyclable. The present NPS/Fe3O4nanocomposites are potential antibacterial materials with magnetically recyclable property.XRD results showed that the rapidly solidified Mg66Cu25.5Sn8.5alloy consists of Mg2Cu and Mg2Sn phases, while both Mg67Cu18Sn15and Mg66Cu10.2Sn23.8alloys consist of Mg2Sn phase. After dealloyed in1wt.%tartaric acid, these Mg-Cu-Sn precursor alloys formed3D nanoporous Cu3Sn, Cu6Sn5and Cu6Sn5-Sn composites, respectively. Li-ion battery discharge/charge tests showed that the as-dealloyed Mg67Cu18Sn15precursor alloys performed excellent cyclic life under the current density of100mA/g.