Design and Synthesis of C-O Grain Boundary Strengthening of Al Composites

Abstract

This research presents an approach for C-O grain boundary strengthening of Al composites that used an in situ method to synthesize a C-O shell on Al powder particles in a vertical tube furnace. The C-O reinforced Al matrix composites (C-O/Al composites) were fabricated by a new powder metallurgy (PM) method associated with the hot pressing technique. The data indicates that Al4C3 was distributed within the Al matrix and an O-Al solution was distributed in the grain boundaries in the strengthened structure. The formation mechanism of this structure was explained by a combination of TEM observations and molecular dynamic simulation results. The yield strength and ultimate tensile strength of the C-O/Al composites, modified by 3 wt.% polyvinyl butyral, reached 232.2 MPa and 304.82 MPa, respectively; compared to the yield strength and ultimate tensile strength of the pure aluminum processed under the same conditions, there was an increase of 124% and 99.3%, respectively. These results indicate the excellent properties of the C-O/Al-strengthened structure. In addition, the strengthening mechanism was explained by the Hall–Petch strengthening, dislocation strengthening, and solid solution strengthening mechanisms, which represented contributions of nearly 44.9%, 15.9%, and 16.6% to the total increased strength, respectively. The remaining increment was attributed to the coupled strengthening of the C and O, which contributed 20.6% to the total increase.

Effect of Cr Segregation on Mechanical Behavior and Deformation Mechanism of Ni─Co─Cr Alloy

“…This is consistent with the results of previous studies. [ 32 ] The mechanical properties of the material as a whole increased linearly. The Cr element introduced at the grain boundary did not cause the mechanical behavior to decrease due to the destruction of the original structure, but with the increase of the content, the performance improved more and more obvious.…”

Structure Characterization and Impact Effect of Al-Cu Graded Materials Prepared by Tape Casting

“…By controlling the blade height of the casting machine, the thickness of the cast film after drying can be controlled. The dried Al-Cu cast film is cut into preset diameters mold, and the cut Al-Cu casts are stacked in sequence according to the designed graded structure [ 34 ]. Then, the whole mold and Al-Cu casts inside are heated under 450 °C to remove the PVB in a vacuum atmosphere.…”

Design of In Situ Metal Matrix Composites Produced by Powder Metallurgy—A Critical Review

“…Oftentimes, in situ and sintering are performed in a single thermal cycle, even though there are reports of powders that underwent special processes in which reinforcement formation took place before the sintering stage [70][71][72][73][74][75]. High temperatures and long reaction periods on the one hand may help in situ reactions and densification, when sintering is simultaneous to those reactions, but on the other hand, they also favor nucleation of larger reinforcements and accelerated coarsening of them.…”

“…It was considered that going directly to the sintering temperature would cause critical radius for precipitation to be larger and, therefore, a smaller number of larger precipitates would tend to be formed directly. It was found that optimum sintering temperature for such a composition to be 1773 K, for it gave rise to a hardness of 1451 ± 22 HV10, transverse rupture strength of 956 ± 64 MPa, and fracture toughness of 10.59 ± 0.30 Oftentimes, in situ and sintering are performed in a single thermal cycle, even though there are reports of powders that underwent special processes in which reinforcement formation took place before the sintering stage [70][71][72][73][74][75]. High temperatures and long reaction periods on the one hand may help in situ reactions and densification, when sintering is simultaneous to those reactions, but on the other hand, they also favor nucleation of larger reinforcements and accelerated coarsening of them.…”