Abstract
<jats:p>To overcome the strength-ductility conflict in particle reinforced aluminum matrix composites (PRAMCs), we propose a novel processing strategy focusing on strength improvements without compromising ductility of PRAMCs. The strategy consists of cryogenic pre-stretching and aging treatment (CPAT), in which the aging treatment can be divided into natural aging (CPAT-T4) and artificial aging (CPAT-T6). The improved mechanical properties are attributed to the sub-grain boundaries (SGBs) introduced by the CPAT process, which reduce the stress concentration at the interface and enable more homogeneous plastic deformation. Additionally, the strain gradient between sub‑grains (hard domain) around SiC particles and the adjacent Al matrix (soft domain) drives geometrically necessary dislocations (GNDs) to accumulate at interfaces to accommodate the gradient, contributing to hetero-deformation-induced (HDI) strengthening. By applying the CPAT process to 15 vol.% SiCp/2009Al composite, the yield strength (YS) of CPAT-T4 and CPAT-T6 samples reaches 439.2 MPa and 472.3 MPa, respectively, increasing significantly by 27.8% and 24.1% compared with those of the conventional T4 and T6 samples, while the elongation of the CPAT samples remains almost unchanged. This work offers valuable guidance for the optimization of thermomechanical treatments for PRAMCs.为了克服颗粒增强铝基复合材料的强度-延性冲突，提出了一种既提高强度又不影响延性的新型加工策略。该策略包括低温预拉伸时效处理（CPAT），其中时效处理可分为自然时效（CPAT- t4）和人工时效（CPAT- t6）。CPAT工艺引入的亚晶界（sgb）降低了界面处的应力集中，使塑性变形更加均匀，从而提高了材料的力学性能。此外，SiC颗粒周围的亚晶粒（硬畴）和相邻的Al基体（软畴）之间的应变梯度驱动几何上必要的位错（GNDs）在界面处积累以适应梯度，有助于异质变形诱导（HDI）强化。对15 vol.% SiCp/2009Al复合材料进行CPAT处理后，CPAT-T4和CPAT-T6的屈服强度（YS）分别达到439.2 MPa和472.3 MPa，较常规T4和T6试样分别显著提高27.8%和24.1%，而CPAT试样的伸长率基本保持不变。本研究为PRAMCs的热力学处理优化提供了有价值的指导。</jats:p>