Tuning Microstructure and Mechanical Performance of a Co-Rich Transformation-Induced Plasticity High Entropy Alloy

Abstract

Multi-principal element alloys and high-entropy alloys (HEAs) are emerging metallic materials with unprecedented structures and properties for various applications. In this study, we tuned the microstructure and mechanical performance of a recently designed high-performance Co-rich TRIP-HEA via thermomechanical processing (TMP). The microstructures of the HEA after various TMP routines were characterized, and their correlation with room-temperature tensile performance was clarified. The results showed that grain refinement is an effective strategy for enhancing strength while retaining satisfactory ductility. The formation of incoherent precipitates slightly improves the strength but inevitably sacrifices the ductility, which needs to be considered for optimizing the TMPs. The room temperature tensile yield strength and ultimate tensile strength were increased from 254.6 to 641.3 MPa and from 702.5 to 968.4 MPa, respectively, but the tensile elongation retains a satisfactory value of 68.8%. We herein provide important insights into the regulation of the microstructure and mechanical properties of TRIP-HEAs.

Achieving Excellent Strength-Ductility Balance in Single-Phase CoCrNiV Multi-Principal Element Alloy

“…Additionally, SFE influences the mechanical properties of alloys by affecting the deformation mechanisms. In cases where the SFE is low, it can not only generate high-density dislocations but also activate twinning-induced plasticity (TWIP) or transformation-induced plasticity (TRIP) effects [34]. To reveal the reasons for comprehensive mechanical properties of CR750 and CR800, the deformation microstructures after tensile tests were characterized using XRD, TEM, and selected area electron diffraction (SAED).…”

“…A higher SFE results in a narrow SF width and frequent cross-slip, leading to a dominant wavy slip behavior. Conversely, When the SFE of the alloys is lower, the partial dislocations with wide spacing will inhibit the cross-slip, and the dislocation slip shows a planar slip mode, and even the TWIP and TRIP effects appear, which improves the comprehensive mechanical properties of the alloys [34]. In CoCrNi alloy with a low SFE, a large number of SFs are often generated during the deformation process, leading to deformation twinning [16].…”

“…In CoCrNi alloy with a low SFE, a large number of SFs are often generated during the deformation process, leading to deformation twinning [16]. Under specific temperature and strain rate conditions, deformation-induced martensite transformation may also occur [34]. However, theoretical calculations indicated that the SFE of VCoNi was higher than that of CoCrNi when the Cr was replaced with the V [30].…”

Control of the Microstructure in a Al5Co15Cr30Fe25Ni25 High Entropy Alloy through Thermo-Mechanical and Thermal Treatments

“…In fact, many results are reported for coarse-grained as-cast materials, which would lead to the frequently low yield strengths reported in the literature [5]. Nevertheless, the microstructure of these alloys could be conveniently refined through the proper design of the processing route [13][14][15][16][17][18][19]. Most of the research in this field was mainly accomplished in equiatomic alloys, showing that the yield strength/ductility of these alloys can be considerably increased through the proper optimization of thermo-mechanical processing [13,14] and/or thermal treatments [15][16][17].…”

Effects of V Addition on the Deformation Mechanism and Mechanical Properties of Non-Equiatomic CoCrNi Medium-Entropy Alloys

“…HEAs/MEAs such as FeMnCoCr, CoCrNi, and FeCoCrNi usually undergo twinning deformation. The martensitic transformation from FCC to hexagonal close-packed (HCP) structure may occur under special temperatures and strain rates [ 6 , 7 ]. Various deformation mechanisms such as twinning-induced plasticity (TWIP) [ 8 ], transformation-induced plasticity (TRIP) [ 9 ], and stacking-fault-induced plasticity [ 10 ] can simultaneously improve the strength and ductility of MPEAs with FCC structures.…”