Influence of Copper Additions in Fe-10Ni (mass %) Alloys on Cooling Microstructures
Austenite/ferrite phase transformations in Fe-xCu-10Ni alloys, 0<x<15 (mass%), are studied under two different cooling conditions, ice-brined quenching or slow cooling in the dilatometer. The influence of copper addition and cooling rate on the microstructure of the alloys is studied. Metallographic examinations of quenched samples show that metastable transformations occur during cooling. As for Fe-Ni alloys, it is impossible to stabilize the high temperature phase (γFeNi) in the Fe-Ni-Cu alloys. Dilatometry measurements of the γ → α transformation temperature with a cooling rate of 2°C/min also indicate a metastable phase formation despite the low cooling rate. For all alloys, a mixture of massive and lath ferrite is observed, one being predominant depending on the cooling conditions and composition. It is shown that the cooling rate has nearly no influence on the microstructure of alloys with a small amount of Cu unlike the alloys containing more Cu. In all alloys containing Cu, nanometric γCu precipitates, much finer in the quenched samples, are detected in the ferrite grains.
Yves Bréchet, Emmanuel Clouet, Alexis Deschamps, Alphonse Finel and Frédéric Soisson
C. Crozet et al., "Influence of Copper Additions in Fe-10Ni (mass %) Alloys on Cooling Microstructures", Solid State Phenomena, Vols. 172-174, pp. 505-510, 2011