Document Type : Research Article

Authors

• Ali Jadidi
• Seyyed Mehdi Abbasi
• Masoume Seifollahi

Metallic Materials Research Center, Malek Ashtar University of Technology, Tehran, Iran

Abstract

The microstructural characteristics of the CMSX-4 single crystal produced by the Bridgman method at a withdrawal rate of 2 mm/min, was investigated through experimental measurements as a function of the distance from chill plate in the present study. The single crystal examined in this research was fabricated using a vertical Bridgman device equipped with a radiation baffle. The microstructural characteristics of the primary dendrite arm spacing (λ₁) and the secondary dendrite arm spacing (λ₂) have been calculated from transverse and longitudinal sections at different distances from the chill plate, using software analysis of images prepared with an optical microscope (OM). The comparison of the obtained values for the microstructural characteristics λ₁ and λ₂ reveals that both variables increase with increasing distance from the chill plate by 19.6% and 18.8%, respectively, in the single crystal. Additionally, the thermal gradient has been calculated based on the primary and secondary dendrite arm spacing and the result obtained from the primary dendrite arm spacing was found to be more reasonable due to its better alignment with experimental values.

Keywords

• Single crystal superalloy
• Bridgman method
• Chill plate
• CMSX-4
• Dendrite arm spacing

Main Subjects

• Casting and molding processes