Mechanical properties of bismuth telluride based alloys with embedded MoS2 nano-particles

• Nanocomposites with embedded MoS2 nano-particles showed drastic grain size reduction.
• Addition of MoS2 nano-particles led to changes in the texture of nanocomposites.
• Hardness and flexural strength of nanocomposites significantly improved ~ 60%.

We present a comprehensive study of the mechanical properties of bismuth telluride based nanocomposites containing MoS2 nano-particles, obtained by mechanical alloying and hot extrusion. The addition of MoS2 nano-particles significantly altered the crystallographic texture of the nanocomposites. Micro- and nano-structure analyses showed a drastic grain size reduction compared to that of conventional single-phase alloys. The nanocomposites improved their hardness and flexural strength by about 60% compared with the MoS2-free samples. The calculated rupture energy showed that more than 100% higher energy for crack propagation is required at a content of 2.5 vol.% MoS2 compared to not reinforced samples. The changes in the flexural elastic modulus may be partially explained by the alteration of texture. The observed enhancement in the mechanical strength and fracture toughness of nanocomposites can be attributed to grain refinement and to residual stress fields induced in the matrix by the introduction of MoS2 nano-particles.

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