To investigate the effect of 5 wt% Al addition on the long-term thermal ageing behavior of 15Cr ODS steel, the age-hardening behavior of 15Cr and 15Cr–5Al ODS steels, which have been isothermally aged at 475 °C for 9000 h, have been studied by tensile test, and the resultant nanoscale structure and chemistry have been characterized by atom probe tomography (APT), transmission electron microscopy (TEM) and energy-filtered transmission electron microscopy (EFTEM). Thermal age-hardening is much more significant in 15Cr–5Al ODS steel, relative to 15Cr ODS steel. The α′ phases are finer and less developed in 15Cr ODS steel, relative to 15Cr–5Al ODS steel, indicating 5 wt% Al addition enhances the Fe–Cr phase decomposition of 15Cr ODS steels. The (Ti, Al)-enriched β′ phases with crystallography related to Heusler-type Fe₂AlTi precipitated in 15Cr–5Al ODS steel during the ageing. Ti partitions predominantly into α′ phases in 15Cr ODS steel whereas Ti partitioning into α phases is much stronger, relative to α′ phases, in 15Cr–5Al ODS steel. The number density of core/shell structured oxide particles is much higher for 15Cr ODS steel, relative to 15Cr–5Al ODS steel. It is considered that the formation of core/shell structured oxide particles should retard α–α′ phase separation. The age-hardening of 15Cr ODS steel was well predicted by the dislocation shearing mechanism of α′ phases, while the more significant thermal age-hardening in 15Cr–5Al ODS steel is attributed to the strengthening of not only α and α′ phases but also the additional β’ phases. 15Cr ODS steel was found to be more thermally stable than 15Cr–5Al ODS steel under the present ageing conditions.

为了研究添加5 wt％的Al对15Cr ODS钢的长期热时效行为的影响，研究了在475°C下等温时效9000 h的15Cr和15Cr-5Al ODS钢的时效硬化行为，已经通过拉伸试验研究了所得的纳米级结构和化学，并通过原子探针层析成像（APT），透射电子显微镜（TEM）和能量过滤透射电子显微镜（EFTEM）进行了表征。相对于15Cr ODS钢，热时效硬化在15Cr-5Al ODS钢中更为重要。相对于15Cr-5Al ODS钢，α'相在15Cr ODS钢中更细且不发达，这表明5wt％的Al添加会增强15Cr ODS钢的Fe-Cr相分解。与Heusler型Fe ₂有关的具有（Ti，Al）富集的β'相的晶体学在时效过程中，AlTi沉淀在15Cr-5Al ODS钢中。在15Cr ODS钢中，Ti主要以α'相分隔，而在15Cr-5Al ODS钢中，相对于α'相，Ti分隔为α相要强得多。与15Cr-5Al ODS钢相比，15Cr ODS钢的核/壳结构氧化物粒子的数量密度高得多。认为核/壳结构氧化物颗粒的形成应延迟α-α'相分离。通过α'相的位错剪切机制可以很好地预测15Cr ODS钢的时效硬化，而15Cr-5Al ODS钢中更重要的热时效硬化不仅归因于α和α'相的强化，还归因于其他的β'相。在目前的时效条件下，发现15Cr ODS钢比15Cr-5Al ODS钢更热稳定。