Q. Discuss the role of precipitate particles, strengthening crystalline materials against yield as low as well as high temperature of deformation.

Ans. Effect of precipitate particles in strengthening:  In case of some alloys there is hardness with time at room temperature or after heating to slightly higher temperatures. This type of hardening is called precipition or age hardening.

            There is no true interface between the precipitate particle and the surrounding matrix. Since the solute atoms are of different size from the solvent atoms, large amount of elastic distortion is observed around the precipitate particle. These coherent precipitate particles are powerful obstacles to the motion of dislocations. This is because the large elastic distortion of the matrix around the particles interacts strongly with the stress field of dislocations.