Evolution of the Microstructure of a CuCr1Zr Alloy during Direct Heating by Electric Current

Round tensile test specimens of an age-hardened CuCr1Zr alloy were subjected to direct electrical current heating in a Gleeble thermal-mechanical simulator at 800 degrees C. The mechanical properties were monitored by the Vickers hardness test, and the changes in the grain structure were examined by light metallography. A quantitative analysis of the size and distribution of fine precipitates during annealing was carried out using transmission electron microscopy (TEM). The grain structure showed a gradient corresponding to the gradient of the temperature on the test piece. Annealing for 60 s at 800 degrees C resulted in a partially (similar to 50%) recrystallized structure with new grains about 45 mu m in diameter. In the as-delivered condition, TEM documented tiny (1 to 4 nm) coherent chromium precipitates inducing strain fields in the matrix. During overaging, the particles lost their coherence and gradually coarsened up to a mean diameter of 40 nm after 300 s at 800 degrees C. The coarsening kinetics obeys Lifshitz, Sloyzov, and Wagner's theory.

Automated summary

Tensile test specimens of an age-hardened CuCr1Zr alloy were subjected to direct electrical current heating at 800 degrees C in a Gleeble thermal-mechanical simulator. Mechanical properties were monitored using Vickers hardness test, while changes in grain structure were examined with light metallography. TEM was used for quantitative analysis of fine precipitates during annealing, showing a gradient grain structure with recrystallized structure after annealing at 800 degrees C. Coarsening kinetics of chromium precipitates during overaging followed Lifshitz, Sloyzov, and Wagner's theory.