Abstract
The sulfur induced embrittlement of polycrystalline nickel (Ni) metal has been a long-standing mystery. It is suggested that sulfur impurity makes ductile Ni metal brittle in many industry applications due to various mechanisms, such as impurity segregation and disorder-induced melting etc. Here we report an observation that the most ductile measurement occurs at a critical sulfur doping concentration, 14 at.% at pressure from 14 GPa up to 29 GPa through texture evolution analysis. The synchrotron-based high pressure texturing measurements using radial diamond anvil cell (rDAC) X-ray diffraction (XRD) techniques reveal that the activities of slip systems in the polycrystalline nickel metal are affected by sulfur impurities and external pressures, giving rise to the changes in the plastic deformation of the nickel metal. Dislocation dynamics (DD) simulation on dislocation density and velocity further confirms the pressure induced ductilization changes in S doped Ni metal. This observation and simulation suggests that the ductilization of the doped polycrystalline nickel metal can be optimized by engineering the sulfur concentration under pressure, shedding a light on tuning the mechanical properties of this material for better high pressure applications.
Highlights
INTRODUCTIONFurther study on the shear stressed S-doped Ni metal samples using recent developed dislocation related synchrotron radial diamond anvil cell (rDAC) texture techniques[7,8,9] can elucidate more details on understanding the embrittlement mechanism of doped Ni metal
The study of embrittlement, or ductility on the other end, of polycrystalline metals due to chemical impurities, such as sulfur (S), hydrogen (H), or phosphor (P) etc., is an important topic in material science, with a wide industrial applications
Later on, based upon first principles simulations, Yamaguchi et al suggested that the dense sulfur segregation at the grain boundary (GB) regions could lead to a large GB expansion and result in the decrease of tensile strength of Ni by one order of magnitude.[2]
Summary
Further study on the shear stressed S-doped Ni metal samples using recent developed dislocation related synchrotron rDAC texture techniques[7,8,9] can elucidate more details on understanding the embrittlement mechanism of doped Ni metal. We performed in-situ synchrotron radiation texture based dislocation characterization to understand the pressure effects on S doped polycrystalline Ni metal’s embrittlement changes and analyzed the underline mechanisms. The DD simulations based on plastic deformation of single crystal model were performed and the results were analyzed to explain the observed abnormal embrittlement changes of S doped Ni polycrystalline metal under high pressure
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