Dynamic tensile deformation and damage of B4C-reinforced Al composites: Time-resolved imaging with synchrotron x-rays

Abstract

a b s t r a c tDynamic tensile experiments are conducted on 15% and 30% in weight percentage B 4 C/Al composites with a split Hopkinson tension bar, along with high-speed synchrotron x-ray digital image correlation (XDIC) to map strain fields at μm and μs scales. As manifested by bulk-scale stress-strain curves, a higher particle content leads to a higher yield strength but lower ductility. Strain field mapping by XDIC demonstrates that tension deformation and tensile fracture, as opposed to shear and shear failure, dominate deformation and failure of the composites. The fractographs of recovered samples show consistent features. The particle-matrix interfaces are nucleation sites for strain localizations, and their propagation and coalescence are diffused by the Al matrix. The reduced spacing between strain localization sites with increasing particle content, facilitates their coalescence and leads to decreased ductility. Designing a particle-reinforced, metallic-matrix composite with balanced strength and ductility should consider optimizing the inter-particle distance as a key parameter.

Anisotropic Mechanical Response and Strain Localization of a Metallic Glassy-Fiber-Reinforced Polyethylene Terephthalate Fabric

“…When the tensile load increases, the cross-section of the specimen decreases gradually, which results in the restraint of warp on weft at the warp and weft intersections and leads to strain localization behaviors. For the 0° and 90° specimens, the fiber bundles parallel to the tensile axis are under an isostrain condition [ 39 ] at lower global strain. It is shown in Figure 7 a,c that the local strain values along both the x- and y-axes seem homogeneous at lower global strains, and most of these local strains are smaller than the global strain.…”

“…Finally, the local strains were computed through the correlation between these images and the initial image of the unloaded specimen using the software. The DIC technique has been applied to investigate the strain development and localization in, for example, anisotropic woven [ 32 , 33 , 34 ], laminate [ 35 , 36 ], and fiber- [ 37 , 38 ] and particle-reinforced composites [ 39 , 40 ].…”

Deformation and fracture of explosion-welded Ti/Al plates: A synchrotron-based study

“…Dynamic mechanical properties of explosion-welded Ti/Al plates have been rarely investigated. For dynamic tension loading, split Hopkinson tension bar (SHTB) has been widely used [23][24][25]. Strain gages are effective for obtaining bulk, rather than meso-scale, responses.…”

“…Local deformation dynamics can 30 be characterized with 2D strain field mapping, using optical digital image correlation [26,27] or x-ray digital image correlation (XDIC) [24, 28,29]. XDIC is advantageous for the penetration capabilities of x-rays, and relies on images acquired with such techniques as x-ray phase contrast imaging [21,30,31], 35 particularly useful in resolving damage and cracking of low-Z, optically opaque, materials [25,30]. Weld or bimetal interface may play a key role in material performance.…”