In this work, the thermoplasticity of hot extruded (HEXed) FGH4096 superalloy was greatly enhanced by sub-solvus temperature holding followed by extremely slow cooling (S-ESC). After S-ESC processing, the dispersed fine γ′ precipitates inside the grains and grain boundaries obviously grow up. Under most deformation conditions, the S-ESCed samples exhibit smaller flow stress and larger strain rate sensitive index (m) values than the HEXed samples, especially the peak value of m is 0.75 vs. 0.32. This is because fine γ′ precipitates limit deformation by pinning dislocation, and coarse γ′ precipitates promote dynamic recrystallization (DRX). Under the high strain rate of 1 s⁻¹, the DRX degree of the HEXed sample is greatly affected by temperature, while the S-ESCed samples maintain a high DRX degree at different temperature. At the high temperature of 1100 °C, the S-ESCed samples exhibit smaller grain sizes and higher DRX degrees than the HEXed sample under low strain rates. More importantly, because the γ′ precipitates promote DRX, the S-ESCed sample achieves superplasticity at 1090 °C and 10⁻³ s⁻¹.

在这项工作中，热挤压 (HEXed) FGH4096 高温合金的热塑性通过亚溶线温度保持和随后的极慢冷却 (S-ESC) 得到极大提高。S-ESC处理后，晶粒内部分散细小的γ'析出物，晶界明显长大。在大多数变形条件下，S-ESCed 样品表现出比 HEXed 样品更小的流变应力和更大的应变率敏感指数 ( m ) 值，尤其是m的峰值为 0.75 和 0.32。这是因为细小的γ'析出物通过钉扎位错限制变形，而粗大的γ'析出物促进动态再结晶 (DRX)。^{在 1 s −1}的高应变率下，HEXed样品的DRX度受温度影响较大，而S-ESCed样品在不同温度下均保持较高的DRX度。在 1100 °C 的高温下，S-ESCed 样品在低应变率下表现出比 HEXed 样品更小的晶粒尺寸和更高的 DRX 度。更重要的是，由于γ'沉淀物促进 DRX，S-ESCed 样品在 1090 °C 和 10 ^-3 s ^-1下实现超塑性。