Fractographic Evaluation of Crack Initiation and Growth in Al-CNTs Nanocomposite Fabricated by Induction Melting

Abstract

Presence of reinforcement material in the matrix plays a vital role in modifying the fracture topography besides mechanisms of deformation and strengthening of a composite. In the present study, Al-CNT composite was prepared using induction melting technique. The composite was cast into copper mold and cold rolled to ≈95% reduction in thickness. In as rolled condition, the composite exhibited a simultaneous increase in yield strength (> 70%), tensile strength (> 50%) and hardness (> 40%). The fracture surfaces of the broken tensile specimens were studied using scanning electron microscope. It was observed that the crack initiation was occurred in the matrix followed by void link-ups for its growth. Micro cracks initiation in the matrix played a vital role to sustain the ductility of the material.

Mechanical Properties of the Pt-CNT Composite under Uniaxial Deformation: Tension and Compression

“…The destruction mechanism is a crucial stage in the process of deformation of such samples. This aspect has been studied in the work [14]. The research reveals the destruction mechanism via the formation of cracks in the metal matrix and their further enlarging to voids.…”

Effect of Carbon Nanotubes Addition on the Formability of Al-CNT Composite

“…Our previous studies proved the significant dispersion is achievable using induction melting process, however the nanotubes did not show enough wetting; therefore, increase in mechanical strengths was restricted [13,22]. In the absence of wetting between the nanotubes and the matrix, the strengthening material (i.e., MWCNTs) provided the strength until certain level, thus an increase in UTS, %E, σn and w factors was observed, beyond which the nanotubes-matrix interface did not hold the strength and acted as stress concentration points to initiate the fracture [21]. Consequently, the factors like n, K, εn and m were lowered than pure aluminium.…”

“…Tensile Toughness (w). Once the n and K values are derived from true stress-true strain diagram, the area under the curve could be calculated using following equation [21]:…”

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