Podeutektoidní NiTi slitina vyrobena in situ z práškové směsi nanášené kinetickýmj naprašováním

HYPO-EUTECTOID NITI ALLOY MANUFACTURED BY CGDS POWDER MIX DEPOSITION AND HEAT TREATEMENT

konferenční sborník (ne článek)

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Bi-metallic Ni-Ti deposits were produced by low-pressure cold spray with air as working gas. The chemical composition of the 8 mm thick deposit was kept in hypoeutectoid concentration of 92/8 at% Ti/Ni. Samples were annealed in argon protective atmosphere at temperatures from 500°C to 1000°C for two hours. Apart from slow cooling, quenching directly from the homogenization at 1000°C was conducted on some samples and subsequent evolution of precipitated eutectoid was studied. Microstructural changes of material character during annealing were evaluated together with changes in the character of fracture behaviour and local micro hardness of the evolved phases. Microstructure and chemistry was evaluated using analytical electron microscopy. DSC study was involved in order to characterize the precipitation behaviour under eutectoid temperature. Gradual evolution of intermetallic phases by diffusion mechanism was observed. The samples general shape was preserved during the heating process although formation of Kirkendall porosity was evident. First occurrence of intermetallic phases was observed at 600°C. The evolved phases incurred by diffusion mechanism and included phases close to Ti2Ni, TiNi, and TiNi3.

Ni-Ti kovové nástřiky byly produkovány nízkotlakým kinetickým naprašováním. Vzorky byly žíhány v ochranné atmosféře argonu při teplotě od 500 ° C do 1000 ° C po dobu dvou hodin. Kromě pomalho chlazení, kalení přímo z homogenizace při teplotě 1000 ° C bylo také provedena u některých vzorků. Mikrostrukturní změny v průběhu žíhání byly hodnoceny společně se změnami v povaze lomového chování a mikrotvrdosti vzniklých fází. Mikrostruktura a chemie byla hodnocena pomocí analytické elektronové mikroskopie. DSC studie byla zapojena za účelem charakterizovat chování pod eutektoidní teplotou. Byl pozorován postupný vývoj intermetalických fází difúzním mechanismem. První výskyt intermetalických fází byl pozorován při 600 ° C. Vyvinuly se fáze Ti2Ni, TiNi a TiNi3.

Bi-metallic Ni-Ti deposits were produced by low-pressure cold spray with air as working gas. The chemical composition of the 8 mm thick deposit was kept in hypoeutectoid concentration of 92/8 at% Ti/Ni. Samples were annealed in argon protective atmosphere at temperatures from 500°C to 1000°C for two hours. Apart from slow cooling, quenching directly from the homogenization at 1000°C was conducted on some samples and subsequent evolution of precipitated eutectoid was studied. Microstructural changes of material character during annealing were evaluated together with changes in the character of fracture behaviour and local micro hardness of the evolved phases. Microstructure and chemistry was evaluated using analytical electron microscopy. DSC study was involved in order to characterize the precipitation behaviour under eutectoid temperature. Gradual evolution of intermetallic phases by diffusion mechanism was observed. The samples general shape was preserved during the heating process although formation of Kirkendall porosity was evident. First occurrence of intermetallic phases was observed at 600°C. The evolved phases incurred by diffusion mechanism and included phases close to Ti2Ni, TiNi, and TiNi3.

Cold Spray, reaction synthesis, intermetallics, diffusion, metallic foam

09.12.2015

University of Limoges

Limoges