ULTRASONIC INVESTIGATION OF CMSX-6 SUPERALLOY AT LOW AND HIGH-TEMPERATURES

The elastic constants C-11, C-44 and C' have been measured as a functi on of temperature in a single crystal of CMSX-6 alloy and from these d ata the bulk, Young's and shear modulj have been deduced, together wit h the anisotropy factor A and the elastic constant C-12. The temperatu re coefficient of the elastic constants C-11 and C-44 becomes graduall y more negative on approaching the melting point of the alloy. This so ftening effect is interpreted in terms of a negative contribution to t he elastic stiffness of the material arising from thermal vacancies wi thin the disordered gamma phase. The anisotropy factor A is found to f all in the typical range of fee metals and the Cauchy relationship (C- 12=C-44) appears to be approximately fulfilled, suggesting that the la ttice cohesion is associated with a field of central forces.