Shu Han, Zhi Wang, Le Li, Shohei Onda, Zhenghao Chen, Jean-Philippe Couzinié, Haruyuki Inui
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引用次数: 0
Abstract
The deformation behavior of Ti-Zr-Nb medium-entropy alloys (MEAs) with the body-centered cubic (BCC) structure has been investigated as a function of the HCP (hexagonal close-packed)-element (Ti and Zr) concentration in compression at temperatures between 50 and 1173 K and is discussed in terms of the extent of lattice distortion quantified as mean-square atomic displacement (MSAD). The temperature dependence of yield stress observed for all the Ti-Zr-Nb MEAs investigated is essentially the same as that observed for conventional BCC metals and alloys, featuring a rapid decrease at low temperatures (T<T1), a plateau at intermediate temperatures (T1≤T<T2) and a rapid decrease again at higher temperatures (T≥T2). The deformation mechanism is converted from the Peierls mechanism at low temperatures (T<T1) to an athermal process involving local pinning of screw dislocations at superjogs presumably by solute cluster arising from non-random distributions of the constituent elements at plateau temperatures (T1≤T<T2), as evidenced by the arc-shaped configurations of screw dislocations bowing-out between pinning points. The extent of lattice distortion (MSAD) increases with higher HCP-element concentration and enhances the resistance to dislocation motion, thereby raising both the thermal stress at 0 K and the athermal stress (i.e., the plateau stress). The increased lattice distortion also leads to the steeper temperature dependence of yield stress at low temperatures (T<T1) resulting in the lower onset temperature (T1) for the plateau.
期刊介绍:
Acta Materialia serves as a platform for publishing full-length, original papers and commissioned overviews that contribute to a profound understanding of the correlation between the processing, structure, and properties of inorganic materials. The journal seeks papers with high impact potential or those that significantly propel the field forward. The scope includes the atomic and molecular arrangements, chemical and electronic structures, and microstructure of materials, focusing on their mechanical or functional behavior across all length scales, including nanostructures.