Abstract

Polycrystalline galena ore, previously deformed in experiments at room temperature, has been annealed at temperatures between 200 degrees and 700 degrees C over periods of up to 30 days. The influence of heating on the galena has been studied by measurement of indentation hardness, by observation of the grain textures, and by X-ray analysis of the preferred crystallographic orientation of grains. Strain hardening during deformation results in the galena having a high indentation hardness of up to 105 VH. This is reduced to 76 VH (the hardness of the undeformed galena) by annealing for 10 days at temperatures of about 300 degrees C. No significant further decrease in indentation hardness occurs with increase in annealing temperature. After heating for 10 days recrystallization begins with nucleation and growth of new grains at temperatures of at least 300 degrees C. Recrystallization results in the development of a fabric in which galena grains have no preferred crystallographic orientation. The differences between the behavior of naturally and experimentally deformed galena in annealing experiments are discussed.

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