Ti-Ag系状態図について

Abstract

The phase diagram of the titanium-silver system has been investigated in the whole range mainly by metallographic examination, X-ray analysis and the thermal analysis method. Only an intermediate compound TiAg was found to exist in this system by X-ray analysis and metallographic examination. The crystal structure of this compound was nearly similar to the report by R. J. Van Thyne et al. and a=4.078 Å, c=4.065 Å and c⁄a=0.996 were determined, A peritectic reaction beta-Ti+Liq.\ ightleftharpoonsTiAg occurs at 1045°C and beta-Ti decomposes into alpha-Ti and TiAg by eutectoid reaction: beta-Ti\ ightleftharpoonsalpha-Ti+TiAg. The eutectoid point was about 23 wt% silver and its temperature lies between 860° and 890°C. The solubility of silver in beta-Ti is about 53 wt% at peritectic temperature and the solubility in alpha-Ti is less than 12 wt% at room temperature but more than 13 wt% at eutectoid temperature. The intermediate compound TiAg extends from 68 wt% to 73 wt% silver at room temperature and its hardness was about 130 kg/mm2 VPN, but the compound was brittle to give any reduction by rolling and could work easily neither at room temperature nor higher temperature. On the silver-rich side, a eutectic reaction Liq.\ ightleftharpoonsTiAg+Ag was observed at 890°C and its composition was about 96 wt% silver. The whole phase diagram which was obtained by these experimental results as shown in Fig. 6.