Residual microstructure associated with impact craters in TiB2/2024Al composite.

School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.
Micron (Impact Factor: 1.88). 02/2012; 43(2-3):344-8. DOI: 10.1016/j.micron.2011.09.011
Source: PubMed

ABSTRACT Residual microstructures associated with hypervelocity impact craters in 55 vol.% TiB(2)/2024Al composite were investigated by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). TiB(2)-Al interface, TiB(2) particles and Al matrix before and after hypervelocity impact were compared to discuss the effect of hypervelocity impact. A new Al(x)O(1-x) phase with the fcc structure and the crystal parameter of 0.69 nm was formed at TiB(2)-Al interface. Stacking fault with width of 10-20 nm was formed along the (001) plane of TiB(2) particle. Formation of nanograins (≈ 100 nm) was observed within Al matrix, moreover, lamellar S' phase was transformed into lenticular or spherical S phase after hypervelocity impact.

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    ABSTRACT: In the present work, B4C/2024Al composites with volume fraction of 45% were prepared by a pressure infiltration method. The microstructure of the crater bottom of B4C/2024Al composite after impact was characterized by transmission electron microscope (TEM), which indicated that recovery and dynamic recrystallization generated in Al matrix, and the grain size distribution was about from dozens of nanometer to 200 nm. Furthermore, the plastic deformation was observed in B4C ceramic, which led to the transformation from monocrystal to polycrystal ceramic grains. The boundary observed in this work was high-angle grain boundary and the two grains at the boundary had an orientation difference of 30°.
    Micron 01/2014; · 1.88 Impact Factor
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    ABSTRACT: Characteristic of dislocations in TiB2 particles associated with hypervelocity impact craters in 65 vol.% TiB2/Al composite were investigated by transmission electron microscopy (TEM). Two kinds of dislocation networks in as-impacted TiB2 particles were identified. One is hexagonal dislocation networks including 1/3〈1¯ 2 1¯ 0〉, 〈0 0 0 1〉, 1/3〈1¯ 2 1¯ 3〉 type dislocations on {0 0 0 1}, {1 0 1¯ 0}, and {1 2 3¯ 0} planes. Another one is the hexagonal dislocation networks including 1/3〈1 1 2¯ 0〉, 〈0 0 0 1〉, and 1/3〈112¯3〉 type dislocations on {0 0 0 1}, {1 0 1¯ 0}, and {1 1¯ 0 0} planes. Formation of dislocation network should be contributed to the parallel sets of “a” type dislocations (1/3〈1 1 2¯ 0〉 or 1/3〈1¯ 2 1¯ 0〉 type dislocations) reacting with parallel sets of “b” type dislocations (〈0 0 0 1〉 type dislocations) to form “c” type dislocations (1/3〈1 1 2¯ 3〉 or 1/3〈1¯ 2 1¯ 3〉 type dislocations). Moreover, dislocations reaction processes do not result in an energy reduction, and are called quasi-equilibrium configurations. Formation of dislocations may result from high temperature or pressure generated by hypervelocity impact. During the cooling from high temperature and unloading from high pressure, dislocations in TiB2 particles rearranged and transformed to dislocation networks to lower the defect energy.
    Micron 01/2014; 67:96–99. · 1.88 Impact Factor