EFFECT OF 3RD ELEMENTS ON CU PRECIPITATION IN FE-CU ALLOYS

In order to investigate the influence of third elements on Cu precipit ation, small-angle neutron scattering (SANS) measurements and atom-pro be (AP) analysis were carried out in conjunction with micro-hardness m easurements during the early stage of phase decomposition in Fe-Cu bas ed alloys. In the present paper, the effect of Ni, Mn and Ag are mainl y reported. Data analysis of SANS intensities far the specimen added b y Mn and Ni showed that the nuclear Guinier radius becomes larger than the magnetic one beyond about 2 nm. This is suggested to be attributa ble to the formation of segregated layer enriched by Ni and Mn around fee copper-rich precipitate. This segregation was confirmed directly b y atom-probe (AP) analysis. The calculated SANS intensities are well f itted to experimental data of both magnetic and nuclear components of neutron scatterings. Small addition of silver was deduced to cause an increase of coherency strain around bcc copper rich clusters.