Data supporting the hierarchically activated deformation mechanisms to form ultra-fine grain microstructure in carbon containing FeMnCoCr twinning induced plasticity high entropy alloy

This article presents data regarding the research paper entitled “Hierarchically activated deformation mechanisms to form ultra-fine grain microstructure in carbon containing FeMnCoCr twinning induced plasticity high entropy alloy [1]”. In this article we provide supporting data for describing the associated mechanisms in microstructure evolution and grain refinement of a carbon-doped TWIP high-entropy alloy (HEA) during thermomechanical processing. Microstructural characterization before and after deformation was performed using scanning electron microscope (SEM) outfitted with EBSD detector and transmission electron microscopy (TEM) were used for microstructure observation and investigation of nanostructure evolution during deformation. Inverse pole figure (IPF) map, grain boundary map and kernel average misorientation map (KAM) were used for systematic analysis of nanostructural evolution and deformed heterostructure consisting of hierarchical mechanical twinning, shear-banding, microbanding and formation of strain-induced boundaries (SIBs).


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This article presents data regarding the research paper entitled "Hierarchically activated deformation mechanisms to form ultra-fine grain microstructure in carbon containing FeMnCoCr twinning induced plasticity high entropy alloy [1] ". In this article we provide supporting data for describing the associated mechanisms in microstructure evolution and grain refinement of a carbon-doped TWIP highentropy alloy (HEA) during thermomechanical processing. Microstructural characterization before and after deformation was performed using scanning electron microscope (SEM) outfitted with EBSD detector and transmission electron microscopy (TEM) were used for microstructure observation and investigation of nanostructure evolution during deformation. Inverse pole figure (IPF) map, grain boundary map and kernel average misorientation map (KAM) were used for systematic analysis of nanostructural evolution and deformed heterostructure consisting of hierarchical mechanical twinning, shear-banding, microbanding and formation of straininduced boundaries (SIBs

Value of the Data
• Data on deformation mechanisms of carbon-doped FeMnCoCr high entropy alloys (HEA) are useful for researchers in metals and alloys research community particularly in the field of mechanical performance of medium and high entropy alloys. • The present data provides insight into the alloy design strategy to overcoming strengthductility trade-off in FCC high entropy alloys by deriving bimodal grain size through thermomechanical processing. • The conjunction results of ultimate tensile strength (UTS) and ductility of the present alloy with various high/medium entropy alloys and steels would provide a useful information on the correlation of the gradient microstructure and mechanical performance of high entropy alloys and steels.

Data Description
Microstructure details and corresponding EBSD maps of the carbon containing Fe 39.5 Mn 40 Co 10 Cr 10 HEA subjected to 32% cold roll reduction is shown in Fig. 1 . The EBSD maps and corresponding misorientation angle profiles were presented in the Mendeley Data repository (" Fig. 1    Cold deformed microstructure of Fe 39.5 Mn 40 Co 10 Cr 10 C 0.5 HEA in Fig. 1 (a)-(c) contains some microstructural heterogeneities such as slip bands, deformation twinning and shear banding which associated with large strain gradients. In order to differentiate local misorientations and orientation gradients in the regions of heterogeneities, EBSD combined with a kernel average misorientation (KAM) map is used. In this study misorientation angle was also used for quantitative measurement of plastic strain at heavy deformed microstructure. As seen in Fig. 1 (d) low KAM values was identified in the matrix which dominated by blue. In contrast, as shown by green in Fig. 1

d high KAM values appeared in the regions of slip bands and twin boundaries (TBs) which related to the high local strain in the regions enclosed by the slip bands and
TBs. Based on definition of misorientation, θ < 15 • is considered as a low angle grain boundaries (LAGB) and θ > 15 • is considered as a high angle grain boundaries (HAGB) [2 , 3] . The point-to-    conducted and was presented in the Mendeley Data repository (" Fig. 7 -load-unload-reload true stress-strain curves. xlsx") Fig. 7 (a, b) presents the LUR test curves for as-received (as homogenized) sample and thermomechanlcally processed HEA with bimodal structure. As shown in Fig. 7 (a) The Fe 39.5 Mn 40 Co 10 Cr 10 C 0.5 HEA with heterostructure exhibits superior strength and ductility, which is mainly attributed to the hetero-deformation induced (HDI) strengthening. Moreover, the hysteresis loops of the alloy with bimodal grain size in Fig. 7 (b) is much wider than that of homogenized sample with homogeneous large grains which is associated with the Bauschinger effect.
Data of mechanical properties of Fe 39.5 Mn 40 Co 10 Cr 10 C 0.5 HEA with heterogenous bimodal structure and some recently investigated TWIP-TRIP high entropy alloys and steels are summarized in Table 1 . It was shown that the bimodal heterogeneous structure formed by thermomechanical processing contributes to strength-ductility enhancement in carbon containing Fe 39.5 Mn 40 Co 10 Cr 10 HEA.

Experimental Design, Materials and Methods
A non-equiatomic Fe 39.5 Mn 40 Co 10 Cr 10 C 0.5 (at%) HEA was cast using vacuum induction melting of Fe, Mn, Co, Cr elements. Purity of used element was higher than 99.9% and carbon black used as a source of 0.5 at% C [1] . The 10 Kg of as cast ingot was remelt for 5 times to ensure the compositional homogeneity. For break down the cast structure and further homogenization, the as-cast ingot was hot-rolled at 900 °C to a thickness reduction of 60%. In order to induce grain refinement after homogenization of hot rolled samples at 1200 °C for 2 hours in Ar atmosphere the alloy was cold-rolled to thickness reduction of 32-84%. Post-cold deformation annealing at 850 °C for 30 min was conducted for 84% cold rolled samples followed and water-quenched. Uniaxial tensile tests were performed using United SFM-10.5-ton tensile testing machine at room temperature and strain rate of 1 × 10 −3 s −1 on the as-received and as-rolled samples [1] . Dogbone shaped tensile specimens with a gauge length of 9 mm and a width of 3.4 mm were used. Tensile tests were executed aligned into rolling direction. Microstructures and nanostructures were examined by EBSD and TEM. The TEM samples were mechanically ground to a thickness of 70 μm using 120-800 grit SiC paper and TEM foils were prepared by twin-jet electrochemical polishing machine with the electrolyte solution consisting of 10 vol% perchloric acid and 90 vol% methanol at −30 °C. Subsequently, TEM analyses were performed on a FEI Tecnai G2 F30 S-TWIN operating at an acceleration voltage of 200 kV.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships which have or could be perceived to have influenced the work reported in this article.