No abstract

High manganese and high chromium steels are attractive as low activation materials for fusion reactors. The microstructural stability of Cr-Mn steels during long term service at around 873 K, however, is not yet fully understood. This study is aimed toward the study of changes in microstructure and mechanical properties of Fe-(12 to 16%)Cr-(10 to 30%)Mn alloys during aging in the temperature range from 773 K to 973 K for up to 3.6 Ms(1000 hrs). As a solution treated at 1373 K for 3.6 ks, a microstructure of α′ + ε + γ is observed in the 15%Mn alloy, ε + γ in 20 to 25%Mn alloys and γ in the 30%Mn alloy, σphase formation is not observed in Fe-12%Cr-Mn alloys except at 30%Mn after aging at 873 K for 3.6 Ms. However, straining by rolling (50%in reduction at room temperature) prior to aging accelerates cr-phase formation. All of the strained Fe-12%Cr-Mn alloys form σphase during aging. In the case of 16%Cr alloys, σphase formation occurs more easily. There are three kinds of mechanisms for σphase formation depending on the manganese content, and increase in manganese content accelerates σ-phase formation. These results suggest that the effect of manganese on σ-phase formation is different from the result shown in the Fe-Cr-Mn alloy diagram published by Schafmeister and Ergang.

A wireless smart-scales system with a face recognition function has been developed as an application for wireless sensor networks. The face recognition employs a wireless camera; and the system automatically identifies a person and stores the weights of all the people that use the system on a server. Two key ultralow-energy circuit techniques were devised for the smart scales. One is a nearly-zero-standby-current circuit that combines a mechanical switch and an electrical CPU-controlled power switch; it reduces the standby power dissipation of the CPU from 1.5 mW to less than 0.1 µW. The other is a super-intermittently-operating circuit with a power-switch transistor and a small resistance; it suppresses the energy dissipation of the wireless camera to just 1/4 of the total energy dissipation. Furthermore, an electromechanical micropower generator with electromagnetic induction further reduces the energy dissipation. It is located under the scales and supplies a power of 75 mW during one second.