The effect of cooling rate of sintering on the strength of sintered Fe-Cu has been studied. The copper content was varied between 0 and 12 weight %.
The tensile test specimens were prepared by usual powder metallurgy techniques. The compacts were sintered at 1120℃ for 40 minutes in hydrogen atmosphere and cooled to room temperature at various cooling rates over several temperature ranges.
The strengths of specimens with more that 2% Cu increased greatly with increasing cooling rates between 850℃ and 600℃ the eutectoid transformation range. For 8% Cu, the ultimate tensile strengths for the fast cooled and slow cooled specimens were about 35 and 20Kg/㎟ respectively. This observation is explained by the decreasing size of the precipitated Cu-rich phase with fast cooling rate in the eutectoid transformation. For 2% Cu specimen, the strength increased with slow cooling rate below 600℃. This is attributed to the precipitation hardening effect of the Cu-rich phase.
In general the strength of sintered Fe-Cu increased with copper content reaching the maximum strength for different Cu contents at various cooling rates.
The effect of cooling rate on dimensional change was found to be negligible.
