Showing papers by "Sushanta Kumar Panigrahi published in 2020"

Effect of in-situ sub-micron sized TiB2 reinforcement on microstructure and mechanical properties in ZE41 magnesium matrix composites

Abstract: ZE41 Mg–TiB2 metal matrix composites with improved mechanical properties were synthesized via a novel processing route. In this process, the Ti–B system was developed without addition of third intermediate metallic Al powder, thereby preventing formation of any undesirable hazardous by-products from salt system (Al–K2TiF6–KBF4) and brittle TiAl3 intermetallic phase from master alloy (Al–Ti–B). Sub-micron sized TiB2 particles (5, 10 and 15 wt%) were reinforced in the ZE41-Mg alloy and the influence of TiB2 particles and its weight fraction on mechanical properties of composite materials were studied in details with an emphasis on microstructural characterization. The microstructural characterization shows reasonable uniform distribution of TiB2 particles in lower weight fraction of reinforcement and strong interfacial bonding with the matrix. A significant enhancement of the strength as well as grain refinement of composite were observed with increased TiB2 particles. The effect of TiB2 particle content on Young's modulus and yield strength was correlated via theoretical/mathematical modeling and experimental investigations. The strengthening mechanisms for strength enhancement of composites were established.

Achieving extraordinary structural efficiency in a wrought magnesium rare earth alloy

Abstract: The opportunities for wrought magnesium products in a wide range of structural and functional materials for transportation, energy generation, energy storage and propulsion are increasing due to th...

Aging response on the stress corrosion cracking behavior of wrought precipitation-hardened magnesium alloy

Abstract: Constant immersion testing and slow strain rate testing (SSRT) are conducted on wrought magnesium alloy in a 3.5 wt% NaCl solution. After solution annealing (SA) at 525 °C for 8 h, the alloy was isothermally aged at 210 °C for 15 h, 48 h, and 144 h to obtain underaged (UA), peak-aged (PA), and overaged (OA) microstructures, respectively. After 32 days of constant exposure in chloride solution, the SA and UA samples showed the lowest (~ 0.10 mg cm−2 day−1) and the highest (~ 0.20 mg cm−2 day−1) weight loss, respectively. SSRT was carried out at an initial strain rate of 10−6 s−1 in air and 3.5 wt% NaCl solution to investigate stress corrosion cracking (SCC) susceptibility. SCC susceptibility index was in the order PA > UA > SA > OA. Intergranular failure morphology on the fractured surface after SSRT in chloride solution can be attributed to micro-galvanic activity between grain boundary second phase and adjacent regions. Comparison of electrochemical measurements in unstressed and stressed conditions indicated two orders of magnitude difference in electrochemical resistance of the alloy.

Hot Workability and Processing Map of Ultrafine-Grained Al/SiC Composite with Different Reinforcement Sizes Under Compressive and Tensile Modes

Abstract: The thermo-mechanical properties of severely deformed ultrafine-grained aluminum composites are extremely important for successful forming in various components under hot-forming conditions. Since the size of reinforcement particles plays a vital role in the forming of composites, the current work was designed to study the hot workability of ultrafine-grained (UFG) AA6063-SiC composite with different sizes of reinforcements [coarse (12 µm), fine (1 µm) and nano (45 nm)]. The optimum processing parameters for the successful forming of UFG composites were derived with processing maps obtained by conducting hot tension and compression tests at different temperatures from 300 °C to 450 °C and at strain rates between 0.001 to 10 s−1. Microstructural observations showed dynamic recrystallization as the dominant deformation mechanism in the stable zones in both tension and compression, while the unstable zones showed an uneven microstructure and microcracks. The activation energy for hot deformation decreased with decreasing particle size. The relationship between kinetic analysis and processing maps was established and interrelated based on their microstructures. The work carried out in the present study provides, for the first time, a quantitative analysis for hot deformation of these UFG composites with varying reinforcement sizes in both tension and compression.