Thermal Stability, Grain Growth Kinetics, and Mechanical Properties of Bulk Ultrafine-Grained AA6063/SiC Composites with
- PDF / 14,298,926 Bytes
- 19 Pages / 593.972 x 792 pts Page_size
- 69 Downloads / 187 Views
ON
THE development of bulk ultrafine-grained (UFG)/nanostructured (NS) metal matrix composites (MMC) is of peak interest due to their enhanced mechanical properties compared with coarse-grained counterparts.[1] Among UFG MMCs, UFG particulate aluminum metal matrix composites (AMMC) have drawn considerable attention in academic research and industrial applications.[2,3] Severe plastic deformation (SPD) methods are being extensively used to develop bulk UFG composites. Accumulative roll bonding (ARB),[4,5] equal channel angular pressing (ECAP),[6] high-pressure torsion (HPT),[7] and friction stir processing (FSP)[8,9] are well-established SPD techniques used to develop bulk UFG composites. These deformation techniques store a high fraction of dislocation density in
O.B. BEMBALGE and S.K. PANIGRAHI are with the Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India. Contact e-mail: [email protected] Manuscript submitted August 25, 2018. Article published online July 2, 2019 4288—VOLUME 50A, SEPTEMBER 2019
the matrix, refine the microstructure in the UFG/NS regime and hence impart extraordinary properties to UFG composites. SPD-processed materials often possess high stored energy. However, this stored energy in UFG/NS composites may lead to high thermal instability and make the microstructure unstable.[10–13] When such composites with UFG/NS grains are subjected to thermal cycles, they have the tendency to minimize the energy for grain growth by decreasing the grain boundary area and result in the loss of UFG/NS structure.[14] Furthermore, in addition to the UFG/NS grain structure, the SPD-processed composite materials also possess fine dislocation structures with a large number of stored dislocations.[15] The density of dislocation changes with a reduction in reinforcement particle size.[16] The dislocation structures are even highly thermally unstable compared to the grain structures developed by various SPD techniques.[4–18] Therefore, the thermal stability of UFG composite materials developed by any SPD process should be thoroughly examined before considering them for any engineering application. The thermal instability of UFG/NS composite materials processed through different SPD techniques is a considerable issue, and only limited studies have been METALLURGICAL AND MATERIALS TRANSACTIONS A
reported addressing this problem.[19–23] The thermal stability of the UFG composite varies with varying SPD processing routes and reinforcement sizes.[24–27] Jafarian et al.[28] stated that the Al/TiC (nano-TiC) composite developed by the ARB process was thermally stable below 523 K for 30 minutes of the heating cycle, with an average grain size of 600 nm. Lipecka et al.[21] reported that the Al/CNT composite developed by the powder metallurgy and hot extrusion method was thermally stable up to 823 K for 10 minutes, with an average grain size of 500 nm. Hitherto, most of the research explorations have been circumscribed to the thermal stability of UFG composites with nano-reinfo
Data Loading...
