Discussion of a Characteristic Temperature in Single Crystal Superalloy DD6

Abstract

It is concluded that there is a characteristic temperature present between 800 ºC and 850 ºC in the single crystal superalloy DD6, symbolized as Tc after the longterm crept microstructures are analysed, with investigation into the fracture mechanism of the specimens with low angle grain boundary (LAB) as well as the relationship between modulus and temperature. When the temperature rises beyond Tc, the rafting microstructure comes to arise in the long-term crept specimens. The cohesive strength of the LAB will be weaker than that of alloy at the condition of the temperature beyond Tc so that the inter granular fracture would arise in the specimens with LAB.