If a precipitate hardened alloy is held at a moderately high

If a precipitate hardened alloy is held at a moderately high temperature for some time its yield strength will gradually decay. Explain why.

Solution

The answer to this question lies in the process involved to create precipitate hardened alloys. Precipitate hardened alloys are created by doing solution treatment at high temperatures for a long enough time such that the dislocations are evenly disbursed. After this, the alloy is quenched . Quenching of the alloys freezes the crystal lattice structure. These evenly disbursed dislocations increase the yield strength of the alloy.

Thus if, the alloy is held at moderately high temperature of some of the dislocations will get relieved and create a coarse dislocation. Thus the yield strength will gradually decay.