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Ageing, Age Hardening, Overageing |
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Age
hardening is the process of controlled precipitation hardening that depends
both upon temperature and time as the process is diffusion controlled.
The diagram shows data for an Al-Cu alloy. For the curve (C) the UTS is
seen to increase for hardening times up to 10 hours at 165 C, after which
the tensile strength of the material starts to decrease with treatment
time. This region of decreasing hardness represents overageing of the alloy. |
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From:
Higgins, "Physical Metallurgy," Arnold (1989) |
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