81st Magnetic Materials Center Seminar
July 17, 2008, 9:00-
7th floor small seminar room, Sengen
Enhanced agehardening behavior of Mg-Bi alloy by Zn addition
T. Sasaki
Mg-Bi alloy is a typical precipitation system, and has a possibility to develop cost effective heat resistant Mg-based alloy. This is because of lower cost of the Bi than that of Rare earth, and Mg3Bi2 phase has high melting temperature of 1043 K leading the microstructure stability at high temperature.
The present study will show the enhanced age hardening behavior of the Mg-Bi alloy by the addition of Zn. The peak hardness increased from 50 HV to 70 HV by the Zn addition. The increased peak hardness is attributed to 1) the introduction of the heterogeneous nucleation sites for the Mg3Bi2 phase by the Zn addition , 2) refinement of the precipitates down to 50 nm and 3) increase in the number of Mg3Bi2 plates lying on the prismatic plane.

Mg-Ca alloys of age hardening development
R. Watanabe
Mg-Ca alloy has good combination of strength ,creep resistance , and low cost. of Nie reported age hardening response of Mg-Ca alloy can be improved by added small amount of Zn. In previous work , I talked Mg-0.3Ca-0.6Zn alloy. In this work, I will show the detail microstructure of Mg-0.3Ca-0.6Zn alloy at peak aging and over aging condition. And I will introduce new composition.

Structure investigation of FeB(CuxAu1-x)2 soft magnetic microwires
Y. Chen
The interest for the study on microwires has increased very much. The first amorphous wires are first discussed since they have been studied for 3 decades and because of their outstanding soft magnetic properties.
The aim of this sutdy is for further understanding of the new invented glassy Fe-(Au Cu)B glass coating microwires. Hysteresis loops with typical shapes of soft magnetic materials have been reported in FeBCu samples. For Au0.5at.% sample display a two-step hysteresis loop with a plateau at zero magnetization. The observed change in the axial magnetization process of Au0.5at.% sample has been explained considering the average distance among adjacent a-Fe,Cu nanosized grains to be smaller than the exchange length reported by N.Lupu et.al. The microstructure of each sample was sutdied by TEM and 3DAP. The result indicated for FeBCu sample spinode decomposition occured during the rapidy cooling process. On the other hand the crystallization of Au0.5at.% sample is much more complicate. The detail of result will be talked at the seminar.