Tensile and Fracture Behavior of DZ68 Ni-base Superalloy

The tensile and fracture behavior of DZ68 directionally solidified Ni-base superalloy was studied in the temperature range of room temperature （RT） to 1000℃. The fracture mode was examined by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results show the tensile strength and yield strength of DZ68 alloy increase slightly with increasing temperature, so that at 760℃ its reach maxima value： 1214 and 1019 MPa, respectively. When the experimental temperature is higher than 760℃, the tensile and yield strengths decrease evidently and the ductility increases remarkably. The fractograph of fracture surface for the tensile specimen at room temperature shows a dimple-ductile fracture mode. The fractograph from 760 to 850℃ shows a slide fracture mode. The fractograph from 900 to 1000℃ exhibits a creep rupture mode with uneven deformation.