Hot isostatic pressing-induced dynamic recrystallization in pure copper: Mechanisms and implications for work hardening enhancement

Abstract

This study investigates the correlation between microstructural evolution and physical properties by focusing on the recrystallization behavior occurring around casting pores in pure copper subjected to hot isostatic pressing (HIP). HIP process was conducted under an argon atmosphere at a fixed pressure of 200 MPa for 2 h, with processing temperatures ranging from 300 °C to 900 °C in 100 °C increments. Phase evolution and microstructural changes near the pores were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). The applied pressure, exceeding the yield strength of copper, induced plastic deformation and localized dislocation accumulation around the pores, which served as the primary driving force for recrystallization. With increasing temperature, the relative density improved from 94.4 % (as-cast) to 98.9 % (HIP 900 °C), while the electrical conductivity increased from 88.7 %IACS to 97.9 %IACS. The dislocation density decreased from 1.43 × 10 ¹ ⁵ m⁻² at 400 °C to 5.00 × 10 ¹ ⁴ m⁻² at HIP 900 °C, accompanied by the formation of recrystallized. Notably, when the HIP temperature exceeded HIP 700 °C, the work-hardening exponent (n) increased to ∼0.44, indicating enhanced mechanical strengthening. This characteristic indicates the material's strong potential for application in the manufacturing of high strength wires and thin film components requiring superior formability and mechanical performance.