Tensile Properties and Deformation Mechanisms of Ni-Co-W Based Superalloy with High á Content

The tensile properties and deformation mechanism of a new Ni-Co-W based wrought superalloy at 400-1000 degrees C were investigated. The results showed that the yield strength below 800 degrees C is essentially unchanged but swiftly decreases above 800 degrees C. The ultimate tensile strength of the alloy remains constant below 500 degrees C, decreases moderately between 500 and 850 degrees C, and decreases rapidly above 850 degrees C. The deformation mechanism of the alloy is dominated by dislocation pairs cutting below 700 degrees C, while a large number of stacking faults (SFs) and some microtwins participate in the deformed alloy at 800 degrees C. The dislocation bypass mechanism starts at 850 degrees C and dominates dislocation movement with increasing temperature. Strong coupling dislocation pairs, SFs, and microtwins are responsible for the low and intermediate temperature strength of the alloy. When the bypass mechanism dominates the dislocation motion, the strength of the alloy decreases swiftly at higher temperatures. The revelation of deformation mechanisms is beneficial to the property regulation and safety application of the new superalloy.