|
چکیده
|
This paper focused on the morphology effects of the low and high boron composite nanoparticles in the Ti-Al-O-B quaternary system on reinforcing the copper metal matrix composite via the accumulative roll bonding. To evaluate the impact of reinforcement composition on nanoparticle structure, the B/(Ti+Al) ratio was increased from 0.8 to 2.4 and it was found that the nanoparticles’ morphology was changed from polygonal to whiskers. Also, the Al18B4O33 and AlB2 were remarkably increased with rising the boron content. The novelty of this work is to find how the nanostructured composite of borates/borides/oxides can reinforce the copper sheets via the accumulative roll bonding process. Hence, the microstructures and mechanical properties of copper sheets over three passes of accumulative roll bonding process were investigated. The results indicated that the morphology of the nanoparticles caused a different anisotropy in the mechanical properties such as hardness, strengths, and deformations in the various directions. The hardness of copper sheets was enhanced from 40 Hv to 79 and 111 Hv by reinforcing with low and high boron content nanoparticles respectively, after three passes of the accumulative roll bonding process. Also, it was found that the nano-whiskers exhibited superior strengthening effects to spherical counterparts that acted as formidable barriers against dislocation movement within the copper matrix. The ultimate tensile strength of specimens was calculated at 197 and 215 MPa, respectively, after three passes of the accumulative roll bonding process. The results revealed a density of dislocations of 1.4×1013 m− 2 for copper sheets reinforced by low boron content nanostructures, escalating to 3.2×1013 m− 2 for high boron content counterparts. These findings highly suggest the borate-boride-oxide nano-whiskers as the effective reinforcement of the metal matrix composites.
|