Fine grains less than 10 μm are usually the prerequisite to superplasticity of alloys. Traditionally, multiple-step rolling and heat treatment are necessary to obtain fine grain microstructure of Al alloys. In this paper, a simple method to achieve superplasticity for 2024 alloys has been proposed. An inhomogeneous 2024–1.5TiC nanocomposite reinforced by TiC threadiness arrays was fabricated via casting and hot extrusion processes. By subsequent annealing, fine α-Al grains with average size of 4.1 μm were obtained. And then, elongation of 405% for the 2024–1.5TiC was achieved at 485 °C with initial strain rate of 3.33 × 10⁻⁴ s⁻¹. According to experimental and theoretical analysis, the deformation is mainly controlled by grain boundary sliding and dislocation slip mechanisms. It was found that TiC nanoparticles accelerated nucleation of α-Al recrystallization during annealing, and the limited space between adjacent TiC threadiness arrays restricted α-Al grain growth. The high nucleation rate and low grain growth rate resulted in the formation of fine grains. Besides, TiC nanoparticles inhibited dynamic grain growth during tensile deformation, which also contributes to the superplasticity.

小于10μm的细晶粒通常是合金超塑性的先决条件。传统上，必须进行多步轧制和热处理以获得铝合金的细晶粒微观结构。本文提出了一种实现2024合金超塑性的简单方法。通过铸造和热挤压工艺制备了由TiC线性阵列增强的不均匀的2024–1.5TiC纳米复合材料。通过随后的退火，获得平均尺寸为4.1μm的细α-Al晶粒。然后，在485°C下，初始应变率为3.33×10 ^-4 s ^-1时，2024–1.5TiC的伸长​​率为405％。。根据实验和理论分析，变形主要受晶界滑动和位错滑动机制控制。结果发现，TiC纳米粒子在退火过程中加速了α-Al再结晶的成核作用，相邻TiC螺纹排列之间的有限空间限制了α-Al晶粒的生长。高的成核速率和低的晶粒生长速率导致形成细晶粒。此外，TiC纳米颗粒抑制了拉伸变形过程中的动态晶粒长大，这也有助于超塑性。