Face-centered Cubic Grains Research Articles

Enhancing mechanical properties of high Cr dual-phase FeCrNi medium-entropy alloy through mutual phase transformation and grain refinement

A high Cr Fe40Cr40Ni20 (at.%) medium-entropy alloy was prepared through vacuum arc melting. The alloy exhibited a dual-phase structure comprising face-centered-cubic (FCC) and body-centered-cubic (BCC) phases in a solid solution state. After annealing and cold rolling, two different heterogeneous structures emerged from the original FCC and BCC phases through mutual phase transformation. Moreover, the alloy exhibited a yield strength, ultimate tensile strength, and total elongation of 1.18 GPa, 1.25 GPa, and 13 %, respectively. The high strength of the alloy was mainly attributed to boundary strengthening and heterogeneous deformation-induced (HDI) strengthening within the two heterogeneous structures. Notably, the effectiveness of HDI strengthening was enhanced owing to the complete encapsulation and constraint of soft zones by hard zones in the heterogeneous structure originating from the BCC phase. Additionally, the deformation ability of the alloy mainly depended on dislocation slips and deformation twinning in recrystallized FCC grains and FCC strip phases, thereby ensuring satisfactory ductility.

Nanotwining induced by tensile fatigue and dynamic impact of laser powder bed fusion additively manufactured CoCrFeNi high-entropy alloy

The laser powder bed fusion (L-PBF) additively manufactured CoCrFeNi high-entropy alloy (HEA), with face-centered cubic (FCC) crystal structure, demonstrates better comprehensive mechanical properties in the building direction (BD). Loading quasi-static, dynamic fatigue, and dynamic separated Hopkinson press bar (SHPB) impact stress conditions along the BD of the L-PBF processed HEA exhibit intriguing microstructural evolution characteristics. The L-PBF generates hierarchical dislocation grids containing numerous cell substructures within the HEA FCC grains, impeding dislocation motion during deformation and improving the strength. When subjected to dynamic fatigue loading, the dislocation grids restrict the mean free path of dislocations and thus trigger the activation of abundant stacking faults. Hence, numerous nanotwins form near the end of the fatigue life. Multiple twinning systems can also be activated under dynamic high-speed impact loading. Especially at a low temperature of 77 K, the stacking fault energy of the CoCrFeNi HEA decreases, resulting in increased activation of nanotwins, exhibiting exceptional toughness and resistance to dynamic loads. Additional twin boundaries also impede dislocation movement for the strain hardening. These findings hold valuable implications for the study of additively manufactured HEA parts working in extreme environments.

The nanocrystalline and high density dislocation-Enabled ultrahigh strength and ductility of Al0.4Co0.5V0.2FeNi high entropy alloy

The evolution of the microstructure and mechanical properties of a vacuum arc melted non-equiatomic Al0.4Co0.5V0.2FeNi high-entropy alloy (HEA) subjected to severe plastic deformation was investigated experimentally and by simulations. The present work explored duplex HEAs, comprising a face-centered cubic (FCC) matrix and a body-centered cubic (BCC) phase, towards outstanding their mechanical responses. The Al0.4Co0.5V0.2FeNi alloys had a duplex structure, i.e., with dispersed B2-phase islands (with sizes of dozens of microns) in several hundred micron-, even millimeter-sized FCC grains. The mechanical properties of this HEA were strongly deformation dependent, i.e., when deformation increased from 30 % up to 60 %, the yield strength and ultimate strength tensile increased from ∼0.9 GPa and 1.0 GPa to ∼1.2 GPa and 1.3 GPa, respectively. During tensile deformation, initial fractures occurred in the FCC phase located close to the interface between the FCC and BCC phases. With an increase of deformation, the fracture degree in the FCC phase got larger, and fractures also appeared in the BCC phase. Combined with the geometric dislocation density calculation results from an electron backscatter diffraction (EBSD) analysis, it can be seen that the dislocation density near the phase interface of FCC was higher, making it more likely to produce defects.

An in-situ formed TiC/FeCoNi medium-entropy composite with excellent combination of mechanical and soft magnetic properties

The utilization of conventional Fe–Co soft magnetic materials (SMMs) as essential materials in electric motors and electromagnets is well-established, however, their mechanical properties cannot be further improved. In order to achieve an excellent balance between mechanical and soft magnetic properties, a novel FeCoNi-based medium entropy composite (MEC) reinforced with in-situ synthesized TiC was designed and prepared via mechanical alloying (MA) and spark plasma sintering (SPS). After the SPS process, the developed MEC exhibited a heterogeneous microstructure consisting of ultra-fine face-centered cubic (FCC) grains, micron-sized FCC grains and in-situ nanosized particles. This resulted in exceptional mechanical properties, with a high tensile yield strength of 910 MPa, combined with a total elongation of 10.9%. The superior mechanical properties of the MEC were attributed to dispersion strengthening, hetero-deformation induced (HDI) strengthening and solid solution strengthening. Additionally, the TiC/FeNiCo MEC also exhibited excellent soft magnetic properties, displaying a high saturation magnetization of 141 emu/g and low coercivity of 619 A/m. Therefore, these results demonstrate the potential of the developed MEC to serve as a promising soft magnetic material (SMM) for future applications.

Heterogeneous microstructural design with a bimodal grain size distribution of a multicomponent alloy by reversion from a strain-induced martensite

The aim of this study was to design a simple thermo-mechanical process for multicomponent alloys by fabrication of bimodal-grained distribution, to improve the strength level without a significant strength-ductility trade-off. The corresponding process used reversion from strain-induced body-centered-cubic (BCC) to face-centered-cubic (FCC). The V10Cr10Fe45Co35 alloy exhibited two-phase microstructure of strain-induced BCC and deformed FCC phases after cold rolling. During reversion annealing, the strain-induced BCC phase reverted to ultrafine FCC grains because the martensitic substructure provided ample nucleation sites, while the deformed FCC grains were recrystallized and grown to relatively coarse grains, leading to a bimodal-grained distribution. The annealing temperature was selected as the temperature immediately above the reversion finish temperature. The corresponding alloy exhibited an excellent combination of strength and ductility over 45,000 MPa % and showed yield strength (nearly 1 GPa) two to three times higher than those of conventional FCC-based multicomponent alloys. This was most likely due to the bimodal-grained distribution and active transformation-induced plasticity in metastable ultrafine FCC grains.

Precipitate-mediated metastability of a hetero-structured ferrous high-entropy alloy with superior strain hardening ability

Excellent strain hardening capability holds the key toward a good strength-ductility combination of high- or medium-entropy alloys (HEAs or MEAs). Generally, metastability engineering and heterostructure are known to be two independent strategies for strain hardening. In this work, a hetero-structured metastable (Fe57.5Co20Cr12.5Ni5Mo3V2)99.8C0.2 HEA was prepared in order to incorporate the merits of metastability and heterostructure in one alloy. The annealing microstructure of this alloy consists of heterogeneous face-centered cubic (FCC) grains decorated with various precipitates, including the intergranular submicron M6C precipitates, the intragranular nano-sized MC and σ phase. These multiscale precipitates can act as both compositional and dimensional regulators of FCC grains, assisted by tailoring the annealing parameters. The decrease of annealing temperature or duration produces a larger-volume fraction of precipitates and induces carbon-lean FCC grains with a bimodal grain size distribution. Such precipitate-mediated metastability can successively activate the strain-induced FCC→HCP→BCC martensitic transformation (SIMT) over a large strain range. The sequential operation of multiple deformation mechanisms, such as stacking faults, continuous SIMT and precipitation strengthening, ensures an extremely high strain hardening peak (∼4000 MPa) at a high strain level (0.37) and, therefore, achieves a superior synergy of ultimate tensile strength (942 MPa) and total elongation (59%).

Effect of grain size on the mechanical properties of Fe-30Mn-6Si biodegradable alloy

Fe-30Mn-6Si belongs to a multi-functional material and is one of the most attractive alloys for use in engineering applications, such as pipe joints, repairing bone defects in load-bearing areas, etc. The present work focuses on the effect of face-centered cubic (FCC) grain size on the FCC → hexagonal close-packed (HCP) martensitic transformation and mechanical properties of the Fe-30Mn-6Si biodegradable alloy (BA). The specimens which were fully recrystallized with different FCC grain sizes ranging from 8.2 to 15.0 μm were obtained by different annealing treatments following rolling. According to the results, Hall-Petch relationship of the Fe-30Mn-6Si BA was fitted as: σy = 58.9 MPa + 1080.4 MPa•μm1/2 dγ–1/2. The ultra-high K value (1080.4 MPa•μm1/2) indicates that the Fe-30Mn-6Si BA may exhibit ultra-high strength in ultra-fine grain structure. Remarkably, the Fe-30Mn-6Si BA annealed at 900 °C for 5 min overcame the strength-ductility trade-off which resulted in the higher yield strength, ultimate tensile strength and fracture elongation than the alloy annealed at 1000 °C for 5 min despite with a smaller grain size. In addition, compared to Mg- and Zn-based BAs, the Fe-30Mn-6Si BA exhibits superior mechanical properties.

Effects of aging time on the microstructural evolution and strengthening behavior of a VCoNiMo medium-entropy alloy

Medium-entropy alloys exhibit remarkable strengthening effects owing to their large solid-solution strength, providing high potential for further improvement of the mechanical properties by distributing secondary strengthening phases. In this respect, an equiatomic VCoNi alloy is an appropriate model alloy owing to its yield strength of approximately 1 GPa, with contributions from lattice and grain boundaries. However, the adoption of precipitation hardening is challenging because the solid-solution phase region is limited, which is obtainable only at high temperatures. In this study, Mo is used to generate strengthening phases and expand the region of a face-centered cubic (FCC) solid-solution phase at lower temperatures. The 10 at% Mo, determined through thermodynamic calculations, has little effect on solid-solution states. In low-temperature aging treatments, an ordered FCC (L12) phase forms first followed by the formation of intermetallic μ and κ phases, which are developed under prolonged heat treatment of up to 48 h. L12, which cannot be expected by thermodynamic calculations as an intermediate phase, results in remarkable strengthening effects with a slight reduction in tensile ductility. However, the (Co,Ni)3V-κ phase grows into the grain interiors and along the FCC grain boundaries forming lamellar structures with μ phase, which reduces ductility and increases strength. Thus, this work suggests that the Mo substitution to V overcomes the limitations of the VCoNi alloy and provides second-phase strengthening by forming homogeneous L12 within a large fraction of the FCC matrix; however, an appropriate heat treatment is required to prevent brittleness by suppressing grain-boundary μ and κ phases.

The Observation of Cellular Precipitation in an Ni36Co18Cr20Fe19Al7 High-Entropy Alloy after Quenching and Annealing.

High-entropy alloys (HEAs) comprise a minimum of five major elements. These alloys show some special characteristics, such as excellent mechanical and high temperature properties. The development of the HEAs requires a knowledge of phase transformations during alloy making procedures. The phase transformations of an Ni36Co18Cr20Fe19Al7 HEA were studied in this research. The alloy underwent hot forging, cold rolling, annealing at and quenching from 1323 K, and isothermal holding at 873 K. The alloy is a single face-centered cubic (FCC) phase in the as-quenched condition. After annealing at 873 K, not only fine coherent L12 particles precipitated homogeneously in the FCC matrix, but lamellae of FCC and L12 phases also developed from the grain boundaries. Both lamellar FCC and L12 grains have a cubic-on-cubic orientation relationship (OR). The composition of the lamellar L12 phase is Ni60Co8Cr6Fe6Al20, and that of the lamellar FCC phase is Ni31Co15Cr28Fe21Al4. Cellular precipitation occurs in the HEA, and the high-temperature FCC (γ) transforms to a lamella of low-temperature FCC (γ1), and an L12 phase, i.e., γ → γ1+L12.

Effect of phase interface on stretch-flangeability of metastable ferrous medium-entropy alloys

The demand for high-strength, lightweight structural materials has been increasing; however, alloys with high mechanical performance often have limitations such as unfavorable bendability and stretch-flangeability. In terms of stretch-flangeability, an unexpected crack occurring on the trim line during sheet metal forming has recently been considered as an issue of concern by the industry and academia, but its cause and solution have not been determined yet. This study investigated the effect of the phase interface generated by deformation-induced martensitic transformation on the stretch-flangeability of metastable ferrous medium-entropy alloys. We prepared three alloys that exhibited different transformation-induced plasticity behaviors by controlling their grain sizes and chemical compositions. It was observed that the transformation activity, which is dependent on the microstructure and phase stability, considerably affects the hole expansion ratio obtained from the hole expansion test. Microstructural analyses revealed that deformation-induced martensite formed a layered structure and the phase interface between the face-centered cubic (FCC) and body-centered cubic (BCC) phases served as a site vulnerable to cracking during stretch-flanging. The decreased transformation activity by grain refinement resulted in an increase in the hole expansion ratio (HER) from 8.6% to 28.4%. On the other hand, when the phase stability is low enough to form athermal martensite during quenching, most of the FCC grains are easily transformed into BCC phase and the phase interface is also decreased during stretch-flanging, resulting in the HER of 22.9%. Therefore, the increment of phase interfaces leads to lower stretch-flangeability. This study sheds lights on expanding the applicability of TRIP-utilized materials to industry by suggesting ways to improve stretch-flangeability.

Dislocation induced FCC twinning at the HCP/FCC interfaces in a deformed Ti-5at.%Al alloy: Experiments and simulations

This paper proposes a new formation route for the face-centered cubic (FCC) twins at the hexagonal close-packed (HCP)/FCC interface in a deformed Ti-5at.%Al alloy. Experimental results show that a FCC band satisfying a prismatic-type (P-type) orientation relationship (OR) with the HCP matrix (defined as “P-type FCC band”) is surrounded by a group of FCC lamellae that align in parallel and satisfy a basal-type (B-type) OR within the HCP matrix (defined as “B-type FCC lamellae”). High-resolution transmission electron microscopy reveals a local {111} twinning relation between the P-type FCC band and the B-type FCC lamellae at their contact boundaries. Molecular dynamics simulations indicate that basal stacking faults initiate from the misfit regions and evolve into the B-type FCC lamellae at the relaxed P-type HCP/FCC interfaces. Then mismatch provides the nucleation source for a full dislocation that continues to slip in the initial FCC grain. Repeating these two processes produces the {111} twinning relation between the new-forming FCC lamellae and the initial FCC grain. Lattice correspondence analysis further interprets the formation route for the {111} twins proposed in the present study from the aspect of crystal geometry.

Double-humped strain hardening in a metastable ferrous medium-entropy alloy by cryogenic pre-straining and subsequent heat treatment

Significant benefits of either heterogeneous microstructures or deformation-induced martensitic transformation (DIMT) in metallic materials stem from their superior strain hardening and tensile properties. Herein, we present an unprecedented strain hardening behavior at 77 K in a ferrous medium-entropy alloy comprising a metastable face-centered cubic (FCC) bimodal microstructure with different grain sizes. Pre-straining yields fine body-centered cubic (BCC) martensites, and subsequent heat treatment causes reverse martensitic transformation from BCC to FCC, affording the bimodal FCC microstructure. Furthermore, the yield strength is enhanced due to the presence of submicron FCC grains and geometrically necessary dislocations (GNDs) that are generated during the pre-straining. Profuse GNDs in reversely transformed FCC promote DIMT. Moreover, when true strain exceeds 0.2, widespread DIMT in the interior of the remaining FCC drastically increases the strain hardening rate and consequently delays necking. The outstanding tensile properties derived from this thermomechanical process are because of the DIMT and hetero-deformation-induced strengthening.

Effects of Al on crack propagation in titanium alloys and the governing toughening mechanism

In this work, molecular dynamics simulation is performed to investigate the effect of Al element on the crack propagation along the {101‾1} twin boundary in Ti alloys with different contents and distribution of Al element during the uniaxial tensile deformation. The results show that increasing Al content obviously promotes the percentage of face-centered cubic (FCC) structure during the deformation process, which hinders the micro-crack propagation and enhances the plasticity and toughness of the Ti–Al alloys. The FCC bands transform from the hexagonal close-packed (HCP) matrix satisfying the basal-type (B-type) orientation relationship (OR) represented by (0001)HCP||(111)FCC and [12‾10]HCP||[11‾0]FCC. The increase of Al element reduces the basal stacking fault (BSF) energy of the HCP structure and thus contributes to the formation of BSFs, which grow into FCC bands with the B-type orientation by the slip of Shockley partial dislocations. The {101‾1} pyramidal SF activated at the crack tip evolves into FCC grains in the Ti–Al alloys following the prismatic-type (P-type) OR with the HCP matrix represented by (101‾0)HCP||(110)FCC and [12‾10]HCP||[11‾0]FCC, during which atomic shear and shuffle is involved.

High density of strong yet deformable intermetallic nanorods leads to an excellent room temperature strength-ductility combination in a high entropy alloy

This paper introduces a new microstructural template for high entropy alloys (HEAs), where the face centered cubic (FCC) complex concentrated solid solution is reinforced with a high density of strong, yet deformable, nanorods of an ordered multi-component intermetallic L12 compound. Thermodynamic modeling has been employed to design this HEA with a large L12 volume fraction. Thermo-mechanical processing by isothermal annealing of the conventionally processed bulk cold-rolled alloy directly at precipitation temperatures, has been applied to produce a high density of uniformly distributed L12 nanorods within refined FCC grains, resulting from concomitant recrystallization and discontinuous precipitation processes. The nanorod morphology of the discontinuous L12 product has been established from three-dimensional atom probe tomography. The refined grains result in a complete coverage of the microstructure with discontinuously precipitated intermetallic nanorods. This nanorod strengthened HEA exhibits an exceptionally high room temperature yield strength of ∼1630 MPa, good tensile ductility of ∼15%, and an ultimate tensile strength of ∼1720 MPa. Furthermore, a single L12 phase alloy, melted based on the precipitate composition in the two-phase FCC + L12 HEA, exhibits very high compressive deformability and strain hardenability, unusual for ordered intermetallic compounds. These results open a new strategy for design of fine-grained microstructures strengthened via ordered intermetallic phases, exploiting the beneficial effects of discontinuous precipitation, for achieving very high room temperature tensile strengths while maintaining good ductility.

The formation of B2-precipitate and its effect on grain growth behavior in aluminum-containing CoCrNi medium-entropy alloy

B2-precipitate formation in Al7.45(CoCrNi)92.55 (at.%) was investigated after two-stage annealing. Prior face-centered cubic (FCC) grain growth has been successfully controlled using the pinning effect of B2-precipitate. Electron backscattered diffraction analysis was utilized to study the preferential growth direction of B2-precipitate during the second-annealing process. B2-precipitate as the partially coherent particle, exhibited Kurjumov-Sachs orientation relationship (OR) with FCC matrix in {111}FCC//{110}B2 plane and 〈110〉FCC//〈111〉B2 direction. This orientation relationship altered the interface of B2-precipitate and FCC grain. The matched OR between B2-precipitate and FCC grain was effectively hindered the grain growth of FCC grain by giving the Zener pinning pressure.

Effects of Al addition on microstructure and mechanical properties of Co-free (Fe40Mn40Ni10Cr10)100−xAlx high-entropy alloys

The high-entropy alloys (Fe40Mn40Ni10Cr10)100−xAlx (x = 0, 5, 8, 10, 15, 20) were obtained by vacuum arc melting. Their microstructure was characterized and the mechanical properties were tested. The Fe40Mn40Ni10Cr10 alloy exhibits a single face centered cubic (FCC) phase. Dual-phase microstructure with body centered cubic (BCC) phase distributing along FCC grain boundaries presents in the alloy with 5 at% Al. Further addition of Al content results in the formation of triplex-phase microstructure consisting of FCC phase and coherent B2 nano-phase embedded in the BCC phase. At the Al content of 20 at%, there are only the BCC and B2 phases in this alloy. The BCC/B2 lattice misfit increases sharply with the Al content, resulting in the transformation of B2 nano-phase morphologies from spherical to cuboidal, and ultimately to rod-like. Addition of Al significantly enhances the strength whilst deteriorates the plasticity. With the Al addition of 10 at%, the alloy exhibits a high strength of 841 MPa along with a ductility of 25%.

Dislocation Induced FCC Twins at the HCP/FCC Interfaces in a Deformed Ti-5Al Alloy: Experiments and Simulations

This paper proposes a new formation route for the face-centered cubic (FCC) twins at the hexagonal close-packed (HCP)/FCC interface in a deformed Ti-5at.%Al alloy. From the experimental results, an FCC band that orients in a prismatic-type (P-type) relationship with the HCP matrix is surrounded by a group of FCC lamellae that align in parallel and orient in a basal-type (B-type) orientation relationship within the HCP matrix. The high-resolution transmission electron microscopy (HRTEM) reveals a local { } twinning relation between the FCC band and the FCC lamellae at their contacting boundaries. Molecular dynamics (MD) simulations indicate that basal stacking faults (BSFs), which later evolve into the FCC lamella in a B-type OR with the HCP matrix, initiate from the misfit regions at the relaxed P-type HCP/FCC interfaces, which then provide the nucleation source for a full dislocation that continues to slip in the initial FCC grain. Repeating these two processes produce the { } twinning relation between the new-forming FCC lamella and the initial FCC grain. The lattice correspondence analysis further interprets the formation route for the { } twins proposed in the present study from the aspect of crystal geometry.

Toughening alpha-Ti by dislocation-induced phase transformation at crack tips

In this paper, molecular dynamics simulation was used to investigate the crack propagation along the {101‾1} twin boundary in titanium bi-crystals during uniaxial tensile deformation. The whole deformation process can be divided into two periods according to the crack propagation speed: (1) the quick crack propagation period in the early deformation stage and (2) the slow crack propagation period in the later deformation stage. The results show although the pyramidal and basal stacking faults induced from crack tips can reduce the stress concentration in the early deformation stage, they are nonetheless inadequate to inhibit the quick crack propagation with a velocity over 100 m/s. Comparatively, the formation of new face-centered cubic (FCC) grains at crack tips in the later deformation stage can blunt the crack, retard crack propagation and thus promote the toughness of the material. The nucleation and growth of the newly formed FCC grains are controlled by different mechanisms. During the quick crack propagation period, complex interactions between <c+a> partial dislocations on pyramidal planes and <a> dislocations on prismatic planes induce retained stacking faults in FCC lamella and new pyramidal stacking faults in hexagonal close-packed (HCP) matrix. The retained stacking faults develop into FCC nuclei as the tensile strain increases. During the slow crack propagation period, the FCC nuclei grow towards HCP phase and develop into a coarser grain that pins the further propagation of the adjacent crack tip. The growth of FCC nuclei is governed by a prismatic-type phase transformation mechanism, which involves atomic shear, shuffle and extra lattice distortion.

Engineering multi-scale B2 precipitation in a heterogeneous FCC based microstructure to enhance the mechanical properties of a Al0.5Co1.5CrFeNi1.5 high entropy alloy

While ordered L12 or gamma prime precipitates in face centered cubic (FCC) based microstructures have been extensively used for strengthening nickel or cobalt base superalloys, and more recently in high entropy alloys (HEAs) or complex concentrated alloys (CCAs), the possibility of exploiting ordered B2 precipitates in FCC-based systems has been relatively less investigated. The present study shows the propensity of developing a heterogeneous microstructure, consisting of two different distributions of FCC grain sizes, and two different size scales of B2 precipitates, within an FCC-based Al0.5Co1.5CrFeNi1.5 HEA/CCA. This alloy composition has been designed using solution thermodynamics-based modeling such that it has a high phase fraction and solvus temperature of the B2 phase. The resulting heterogenous microstructure exhibited an approximately 400% increase in yield strength with respect to the single-phase FCC solid solution condition of the same alloy while maintaining very good tensile ductility ∼20%.

A TRIP-assisted dual-phase high-entropy alloy: Grain size and phase fraction effects on deformation behavior

We present a systematic microstructure oriented mechanical property investigation for a newly developed class of transformation-induced plasticity-assisted dual-phase high-entropy alloys (TRIP-DP-HEAs) with varying grain sizes and phase fractions. The DP-HEAs in both, as-homogenized and recrystallized states consist of a face-centered cubic (FCC) matrix containing a high-density of stacking faults and a laminate hexagonal close-packed (HCP) phase. No elemental segregation was observed in grain interiors or at interfaces even down to near-atomic resolution, as confirmed by energy-dispersive X-ray spectroscopy and atom probe tomography. The strength-ductility combinations of the recrystallized DP-HEAs (Fe50Mn30Co10Cr10) with varying FCC grain sizes and HCP phase fractions prior to deformation are superior to those of the recrystallized equiatomic single-phase Cantor reference HEA (Fe20Mn20Ni20Co20Cr20). The multiple deformation micro-mechanisms (including strain-induced transformation from FCC to HCP phase) and dynamic strain partitioning behavior among the two phases are revealed in detail. Both, strength and ductility of the DP-HEAs increase with decreasing the average FCC matrix grain size and increasing the HCP phase fraction prior to loading (in the range of 10–35%) due to the resulting enhanced stability of the FCC matrix. These insights are used to project some future directions for designing advanced TRIP-HEAs through the adjustment of the matrix phase's stability by alloy tuning and grain size effects.