Mössbauer Analysis of Deformation–Induced Acceleration of Short-Range Concentration Separation in Fe-Cr Alloys—Effect of the Substitution Impurity: Sb and Au

Valery Shabashov,Evgenii Novikov,Andrey Zamatovskii,Kirill Kozlov,Yurii Ustyugov,Timofey Tolmachev

doi:10.3390/met10060725

Valery Shabashov, Evgenii Novikov + Show 4 more

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https://doi.org/10.3390/met10060725

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Abstract

The effect of doping the ferrite alloy Fe-16Cr by the oversized impurities Sb and Au on the mechanism of the short-range ordering induced by “warm” severe plastic deformation was studied using the method of Mössbauer spectroscopy. A comparison between the results obtained and the positron annihilation data on the evolution of the defects of vacancy type stabilized by the impurities Sb and Au was performed. It has been established that the impurities Sb and Au entail a shift of the temperature region of short-range ordering realization in conditions of applying pressure torsion towards greater temperatures by 250 and 100 K, respectively.

Highlights

A saturation of the structure of metallic systems upon their severe plastic deformation with point defects is a feature typical of dissipation of a great amount of mechanical energy in these systems, a consequence of which are the anomalous phase transitions occurring at relatively moderate temperatures, dynamic recrystallization, non-equilibrium and equilibrium atomic diffusion, as well as nanostructurization [1,2,3,4,5]
Via methods of Mössbauer spectroscopy, there has been studied the mechanism of the short-range ordering induced by severe plastic deformation of/in the ferritic binary alloy Fe–16Cr, as well as in the alloys Fe-16Cr-0.3Sb and Fe-16Cr-0.13Au doped with Sb and Au
The conditional presence is established of two temperature regions of changing of the degree of short-range ordering in the course of high pressure torsion (HPT) action, namely, the region of “cold” deformation after which the degree of SR order (SRO)

Summary

Introduction

A saturation of the structure of metallic systems upon their severe (mega) plastic deformation with point defects is a feature typical of dissipation of a great amount of mechanical energy in these systems, a consequence of which are the anomalous phase transitions occurring at relatively moderate temperatures, dynamic recrystallization, non-equilibrium and equilibrium atomic diffusion, as well as nanostructurization [1,2,3,4,5]. In a number of iron-based alloys, there has already been shown the twofold effect of severe plastic deformation on the processes of atomic redistribution: on the one hand, disordering stipulated by movement of dislocations and, on the other hand, ordering taking place due to generating moveable vacancy complexes [3,6,7,8]. In this case, the result of influence depends on the temperature of the influence and is determined by concurrency of the processes of disordering (preferentially at “cold” deformation, T ≤ Troom ) and ordering Based on the results obtained, a conclusion was drawn on that accelerated ordering is the consequence of (the presence of) moveable vacancy complexes

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