The effect of ductility minimum temperature in CuNi25 alloy

On the basis of high temperature ductility tests in single-phase cupronickel CuNi25 sample has been found a relation between microstructure, grain size and effect of ductility minimum temperature (DMT). Metallographic tests confirmed literature studies that cracks nucleate at points of two or three grain joints and cross-cut of twined grain with border of the grains. The non-homogeneous character of chemical composition concentrating in areas of grain joints and cracks at high temperature has been investigated by linear and point Cu and Ni analysis (EDS). This analysis shows that local areas of non-equilibrium formation concentrate at this places. This fact can be accepted as one of the reasons of non-homogeneous deformation, cracking and its location at DMT. Experimental results were compared with two-dimensional finite element method (FEM) simulation results of proposed hypothesis of non-uniform deformation.