| Summary: | Experiments were carried out with 1 micron copper powder compacts containing up to 7.5 vol % .018 micron alumina, and with various types of lead powder compacts containing up to 20 vol % of various other materials.
The results indicate that dispersion-hardened alloys should be divided into three groups on the basis of the nature of the second phase.
i) particulate, adherent (not coherent) with matrix
ii) particulate, non-adherent with matrix
iii) semi-continuous
It is suggested that the room temperature strengthening of the second and third groups of alloys may be due primarily to a grain size effect as described by the Hall-Petch relationship.
The cell-like structure recently proposed for S.A.P. has been observed in the lead-lead oxide system by electron microscopy.
An explanation of the difference in properties between extruded and rolled dispersion-hardened alloys has been offered in terms of the directional deformation caused by rolling. === Applied Science, Faculty of === Materials Engineering, Department of === Graduate
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