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Abstract
The dispersion-strengthening of carbonyl iron by alumina and zirconia has been found to be sensitive to particle morphology. This has been studied by optical and electron microscopy in samples representing each stage of various production sequences.
In the case of alloys that had been sintered at 1350°C and then forged and cold rolled, alumina had a greater room-temperature-strengthening effect than did zirconia; whereas for alloys sintered at the same temperature but tested in the extruded condition there was no such difference. Furthermore, sintering at 1200°C followed by forging and cold rolling produced a similar degree of dispersion-strengthening for each of the two dispersoids. These observations are interpreted in terms of the variation of particle morphology with production history.
Tensile properties were also determined in the range 20–600°C for alloys that had been sintered at 1350°C and extruded. The dispersion-strengthening effect decreased with increasing temperature in a manner that is consistent with the experimentally determined recrystallization temperature of these alloys.
Notes
* Manuscript received 9 December 1968. Based on a paper presented at the Second European Powder Metallurgy Symposium held at Stuttgart in May 1968.