Crystallographic Orientation Dependence of Mechanical Responses of FeCrAl Micropillars

Dongyue Xie,Binqiang Wei,Wenqian Wu,Jian Wang

doi:10.3390/cryst10100943

Abstract

Iron-chromium-aluminum (FeCrAl) alloys are used in automobile exhaust gas purifying systems and nuclear reactors due to its superior high-temperature oxidation and excellent corrosion resistance. Single-phase FeCrAl alloys with a body centered cubic structure plastically deform through dislocation slips at room temperature. Here, we investigated the orientation dependence of mechanical responses of FeCrAl alloy through testing single-crystal and bi-crystal micropillars in a scanning electron microscopy at room temperature. Single-crystal micropillars were fabricated with specific orientations which favor the activity of single slip system or two slip systems or multiple slip systems. The strain hardening rate and flow strength increase with increasing the number of activated slip system in micropillars. Bi-crystal micropillars with respect to the continuity of slip systems across grain boundary were fabricated to study the effect of grain boundary on slip transmission. The high geometrical compatibility factor corresponds to a high flow strength and strain hardening rate. Experimental results provide insight into understanding mechanical response of FeCrAl alloy and developing the mechanisms-based constitutive laws for FeCrAl polycrystalline aggregates.

Highlights

Iron-chromium-aluminum (FeCrAl) alloys was initially developed by General Electric (GE)Corporation in the 1960s
The self-interaction of dislocations refers to the interaction between dislocations belonging to the the same slip system
We selected grains with specific orientation in a polycrystalline sample according to the Schmidthe factor (SF) analysis analysis on each slip system with Euler angle measured from electron backscatter diffraction (EBSD) mapping

Summary

Introduction

Iron-chromium-aluminum (FeCrAl) alloys was initially developed by General Electric (GE). This material exhibits superior high-temperature oxidation and excellent corrosion resistance, and were used in automobile exhaust gas purifying systems and nuclear reactors [1,2]. Single-phase FeCrAl alloys with a body centered cubic (BCC) structure plastically deform through dislocation slips. Numerous efforts were made to develop constitutive models based on the knowledge of crystal defects, such as dislocations, twins and grain boundaries [5,6,7,8,9,10,11,12]. Yielding strength of a material is determined by the glide of dislocations, in turn, the glide resistance of dislocations associated with different slip systems is the essential parameter. Strain hardening effect is mainly ascribed to dislocation interactions and/or dislocation-grain boundary interactions

Methods

Results

Conclusion