Combined effect of nanoparticle and grain refinement on yield stress of nanocomposite

ABSTRACT

Considering a high resistance to plastic deformation as a major requirement for many applications of modern engineering materials, the combined effects arising from grain refinement and second-phase nanoparticle on the enhanced strengthening of nanocomposites are predicted. In this work, we investigate when the external critical stress is applied, the splitting transformation of grain boundary dislocations (GBDs) within the double ended pile-ups at TJs (carriers of GB sliding) occurs, which initiates at the onset of yielding and serves as a channel of plastic deformation. In the framework of the model considered, the total energy change characterising this process is attained using the complex potential method for plane elasticity. The influence of the material elastic dissimilarity, lattice misfit strain, the radii of nanoparticle and grain size, geometric parameters of triple junctions (TJs), pile-up number of GBD dipoles and the interface stress on the energy and critical conditions for such a splitting is revealed quantitatively, and then the contribution of each factor to yield stress of nanocomposite has been evaluated more deeply. The theory predicts that grain refinement and second-phase nanoparticle strengthening interact significantly, strongly influence the GBD splitting and then yield stress. It contributes to understanding of the possible influence of these parameters for the effects of microstructure on the deformation behaviour of nanocomposites, which can help guiding the development of nanocomposite with enhanced strength and ductility.

Highlights

• Effects of grain refinement and nanoparticle on splitting of GBD are predicted.

• Splitting of GBDs within double ended pile-ups (carriers of GB sliding) occurs.

• Analytic solution of energy change characterising this process is derived.

• Reveal quantitatively energy and critical conditions for initiating these processes.

• Grain refinement and nanoparticle interact significantly, impacting yield strength.

• Characterise effect of microstructure interactions on predominant mechanism.

KEYWORDS:

• Nanoparticle
• grain refinement
• analytical solution
• critical condition
• yield stress

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

The authors would like to deeply appreciate the support from the NNSFC (11602170) and China Postdoctoral Science Foundation (2016M590199).