Investigation on recrystallization and precipitation behaviors of Al-4.5Cu-1.5 Mg alloy refined by Ti-supported TiC nanoparticles

• Published in: Journal of alloys and compounds 2019-09, Vol.800, p.392-402
• Main Authors: Zhao, Bingyi, Cai, Qizhou, Cheng, Jingfan, Yang, Songfeng, Chen, Fei
• Format: Article
• Language: English
• Subjects: Al-4.5Cu-1.5 Mg alloy; Aluminum base alloys; Copper; Copper base alloys; Dislocations; Elongation; Grain boundaries; Grain size; Nanoparticles; Precipitates; Precipitation behaviors; Recrystallization; Strengthening mechanism; Substrates; TiC nanoparticles; Titanium base alloys; Titanium carbide
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.05.323

The recrystallization and precipitation behaviors of an Al-4.5Cu-1.5 Mg alloy refined by Ti-supported TiC nanoparticles (NPs) (TiC/Ti refiner) were investigated in detail, and the strengthening mechanism was discussed. The results indicated that the addition of TiC/Ti refiner promoted recrystallization of the Al-Cu-Mg alloy and decreased the average grain size to 76 μm. In the aging process, a portion of the dispersed TiC NPs acted as the substrate for S′ to precipitate from the matrix along Al direction, because of the satisfactory matching relationship between the S′ (021)//Al (001)//TiC (001) planes. At the same time, the addition of TiC NPs decreased the precipitate-free zones and refined the grain boundary precipitates in the alloy. The NPs also promoted the precipitation of GPB zones and S′ phases, which reduced the cracking tendency, inhibited the dislocation motion and increased the comprehensive performance of the alloy. As a result, the yield strength, tensile strength and elongation of the TiC/Ti-refined Al-4.5Cu-1.5 Mg alloy reached 287 MPa, 421 MPa and 25.5%, indicating an increase of 22.6%, 14.7% and 109.1%, respectively, compared to the unrefined alloy. In the solution treatment process, parts of single TiC nanoparticles could act as the nucleation substrate for recrystallized grains and promote the recrystallization of Al-Cu-Mg alloy. While in the ageing process, TiC nanoparticles were also beneficial for the precipitation of GPB zone and S′ phase, no matter the single nanoparticle or the clusters. [Display omitted] •TiC/Ti refiner promoted the recrystallization of Al-Cu-Mg alloy.•The TiC nanoparticle was beneficial to the precipitation of GPB zone and S′ phase.•The matching relationship between S′ (021)//Al (001)//TiC (001) was observed.•The yield and tensile strength increased by 22.6% and 14.7% respectively.