Metastable β-Ti alloys exhibiting twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP) generally have excellent ductility, but typically at the expense of relatively low yield strengths whi...Metastable β-Ti alloys exhibiting twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP) generally have excellent ductility, but typically at the expense of relatively low yield strengths which has restricted their widespread use. Our work shows that interstitial oxygen can be employed to regulate β phase stability to significantly enhance both strength and ductility of TWIP/TRIP alloys. For a Ti-32Nb wt.% base alloy, inclusion of 0.3 wt.% O enhanced ductility by more than 140 %, reaching up to 54 % strain, and improved the tensile yield strength by over 95 % to 632 MPa. Compared to other common engineering alloys such as Ti-45Nb, elongation was increased by 29 %, and the yield strength increased by 182 MPa, respectively. Here, we elucidate on impacts of oxygen doping on TWIP/TRIP behaviors in the Ti-32Nb alloy. We reveal that oxygen regulates the critical stress for martensitic transformation, twinning, and dislocation slip. At lower oxygen doping concentrations (≤0.3 wt.% O), multi-stage martensitic transformation and martensitic twinning resulted in high ductility. In higher oxygen content alloys (≥0.5 wt.% O), deformation occurred initially via twinning, while strain induced martensite was subsequently induced in retained β phase regions. Oxygen concentrations control the deformation mechanisms, providing a flexible means to synergistically balance an alloy's strength and ductility. The use of oxygen to enhance stability of the β phase and regulate deformation behaviors is a promising new approach for creating high-performance TWIP/TRIP metastable β-Ti alloys with outstanding mechanical properties.展开更多
Twinning-induced plasticity (TWIP) steel shows great potential in engineering due to its excellent strength and ductility synergy, and strengthening research on its corrosion resistance and high-temperature oxidation ...Twinning-induced plasticity (TWIP) steel shows great potential in engineering due to its excellent strength and ductility synergy, and strengthening research on its corrosion resistance and high-temperature oxidation resistance is critical for broader applications. Herein, the effect of annealing temperature on the high-temperature oxidation and corrosion behavior of Fe-Mn-Cr-Al-Cu-C TWIP steel is investigated. The results show that increasing the annealing temperature from 700℃ to 1100℃ reduced the mass gain of the TWIP steel oxidized at 800℃ for 8 h from 1.93 to 0.58 mg·cm^(−2). Additionally, the self-corrosion current density decreases from 6.52 × 10^(−6) to 1.32 × 10^(−6) A·cm^(−2), while charge transfer resistance increases from 1461 to 3339 Ω·cm^(−2). The reduction in grain boundaries and dislocation density in the TWIP steel attributed to the increase in annealing temperature inhibits short-circuit diffusion, local galvanic corrosion and pitting, ultimately improving both oxidation and corrosion resistance. Moreover, high-temperature annealing prevents the formation of carbon-rich compounds and ensures uniform element distribution. The accumulation of Cu and Cu-rich products formed at the interface further protects against Cl− erosion, inhibiting pitting and local corrosion, thus enhancing the corrosion resistance of the TWIP steel.展开更多
Designing high-performance high-entropy alloys(HEAs)with transformation-induced plasticity(TRIP)or twinning-induced plasticity(TWIP)effects requires precise control over stacking fault energy(SFE)and phase stability.H...Designing high-performance high-entropy alloys(HEAs)with transformation-induced plasticity(TRIP)or twinning-induced plasticity(TWIP)effects requires precise control over stacking fault energy(SFE)and phase stability.However,the vast complexity of multicomponent systems poses a major challenge for identifying promising candidates through conventional experimental or computational methods.A high-throughput CALPHAD framework is developed to identify compositions with potential TWIP/TRIP behaviors in the Cr-Co-Ni and Cr-Co-Ni-Fe systems through systematic screening of stacking fault energy(SFE),FCC phase stability,and FCC-to-HCP transition temperatures(T0).The approach combines TC-Python automation with parallel Gibbs energy calculations across hundreds of thousands of compositions,enabling efficient extraction of metastable FCC-dominant alloys.The high-throughput results find 214 compositions with desired properties from 160,000 candidates.Detailed analysis of the Gibbs energy distributions,phase fraction trends,and temperature-dependent SFE evolution reveals critical insights into the thermodynamic landscape governing plasticity mechanisms in HEAs.The results show that only a narrow region of the compositional space satisfies all screening criteria,emphasizing the necessity of an integrated approach.The screened compositions and trends provide a foundation for targeted experimental validation.Furthermore,this work demonstrates a scalable,composition-resolved strategy for predicting deformation mechanisms in multicomponent alloys and offers a blueprint for integrating thermodynamic screening with mechanistic understanding in HEA design.展开更多
Graphene(Gr)reinforced high-entropy alloy(HEA)matrix composites are expected as potential candidates for next-generation structural applications in light of outstanding mechanical properties.A deep comprehension of th...Graphene(Gr)reinforced high-entropy alloy(HEA)matrix composites are expected as potential candidates for next-generation structural applications in light of outstanding mechanical properties.A deep comprehension of the underlying deformation mechanisms under extreme shock loading is of paramount importance,however,remains lacking due to experimentally technical limitations in existence.In the present study,by means of nonequilibrium molecular dynamics simulations,dynamic deformation behaviors and corresponding mechanisms in equiatomic FeNiCrCoCu HEA/Gr composite systems were investigated in terms of various shock velocities.The resistance to dislocation propagation imparted by Gr was corroborated to encourage the elevated local stress level by increasing the likelihood of dislocation interplays,which facilitated the onset of twins and hexagonal close-packed(HCP)martensite laths.Meanwhile,the advent of Gr was demonstrated to endow the HEA with an additional twinning pathway that induced a structural conversion from HCP to parent face-centered cubic(FCC)inside HCP martensite laths,different from the classical one that necessitated undergoing the intermediate procedure of extrinsic stacking fault(ESF)evolution.More than that,by virtue of an increase in flow stress,the transformation-induced plasticity(TRIP)effect was validated to be additionally evoked as the predominant strain accommodation mechanism at higher strains on the one hand,but which only assisted plasticity in pure systems,and on the other hand,can also act as an auxiliary regulation mode together with the twinning-induced plasticity(TWIP)effect under intermediate strains,but with enhanced contributions relative to pure systems.One may expect that TRIP and TWIP effects promoted by introducing Gr would considerably inspire a synergistic effect between strength and ductility,contributing to the exceptional shock-resistant performance of FeNiCrCoCu HEAs under extreme regimes.展开更多
This study proposes a novel strategy for the design of a new family of metastable Zr alloys.These al-loys offer improved mechanical properties for implants,particularly in applications where conventional stainless ste...This study proposes a novel strategy for the design of a new family of metastable Zr alloys.These al-loys offer improved mechanical properties for implants,particularly in applications where conventional stainless steels and Co-Cr alloys are currently used but lack suitability.The design approach is based on the controlled twinning-induced plasticity(TWIP)effect,significantly enhancing the ductility and strain-hardenability of the Zr alloys.In order to draw a“blueprint”for the compositional design of biomedical T WIP(Bio-T WIP)Zr alloys-using only non-toxic elements,the study combines D-electron phase stability calculations(specifically bond order(Bo)and mean d-orbital energy(Md))with a systematic experimental screening of active deformation mechanisms within the Zr-Nb-Sn alloy system.This research aids in ac-curately identifying the TWIP line,which signifies the mechanism shift between TWIP and classic slip as the primary deformation mechanism.To demonstrate the efficacy of the TWIP mechanism in enhancing mechanical properties,Zr-12Nb-2Sn,Zr-13Nb-1Sn,and Zr-14Nb-3Sn alloys are selected.Results indicate that the TWIP mechanism leads to a significant improvement of strain-hardening rate and a uniform elongation of∼20%in Zr-12Nb-2Sn,which displays both{332}<113>mechanical twinning and disloca-tion slip as the primary deformation mechanisms.Conversely,Zr-14Nb-3Sn exhibits the typical mechan-ical properties found in stable body-centered cubic(BCC)alloys,characterized by the sole occurrence of dislocation slip.Cell viability tests confirm the superior biocompatibility of Zr-Nb-based alloys with deformation twins on the surface,in line with existing literature.Based on the whole set of results,a comprehensive design diagram is proposed.展开更多
基金supported by the Key R&D Program of Zhejiang(No.KZ7240079).
文摘Metastable β-Ti alloys exhibiting twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP) generally have excellent ductility, but typically at the expense of relatively low yield strengths which has restricted their widespread use. Our work shows that interstitial oxygen can be employed to regulate β phase stability to significantly enhance both strength and ductility of TWIP/TRIP alloys. For a Ti-32Nb wt.% base alloy, inclusion of 0.3 wt.% O enhanced ductility by more than 140 %, reaching up to 54 % strain, and improved the tensile yield strength by over 95 % to 632 MPa. Compared to other common engineering alloys such as Ti-45Nb, elongation was increased by 29 %, and the yield strength increased by 182 MPa, respectively. Here, we elucidate on impacts of oxygen doping on TWIP/TRIP behaviors in the Ti-32Nb alloy. We reveal that oxygen regulates the critical stress for martensitic transformation, twinning, and dislocation slip. At lower oxygen doping concentrations (≤0.3 wt.% O), multi-stage martensitic transformation and martensitic twinning resulted in high ductility. In higher oxygen content alloys (≥0.5 wt.% O), deformation occurred initially via twinning, while strain induced martensite was subsequently induced in retained β phase regions. Oxygen concentrations control the deformation mechanisms, providing a flexible means to synergistically balance an alloy's strength and ductility. The use of oxygen to enhance stability of the β phase and regulate deformation behaviors is a promising new approach for creating high-performance TWIP/TRIP metastable β-Ti alloys with outstanding mechanical properties.
基金support from the National Natural Science Foundation of China(Grant No.52174359)is greatly acknowledged.
文摘Twinning-induced plasticity (TWIP) steel shows great potential in engineering due to its excellent strength and ductility synergy, and strengthening research on its corrosion resistance and high-temperature oxidation resistance is critical for broader applications. Herein, the effect of annealing temperature on the high-temperature oxidation and corrosion behavior of Fe-Mn-Cr-Al-Cu-C TWIP steel is investigated. The results show that increasing the annealing temperature from 700℃ to 1100℃ reduced the mass gain of the TWIP steel oxidized at 800℃ for 8 h from 1.93 to 0.58 mg·cm^(−2). Additionally, the self-corrosion current density decreases from 6.52 × 10^(−6) to 1.32 × 10^(−6) A·cm^(−2), while charge transfer resistance increases from 1461 to 3339 Ω·cm^(−2). The reduction in grain boundaries and dislocation density in the TWIP steel attributed to the increase in annealing temperature inhibits short-circuit diffusion, local galvanic corrosion and pitting, ultimately improving both oxidation and corrosion resistance. Moreover, high-temperature annealing prevents the formation of carbon-rich compounds and ensures uniform element distribution. The accumulation of Cu and Cu-rich products formed at the interface further protects against Cl− erosion, inhibiting pitting and local corrosion, thus enhancing the corrosion resistance of the TWIP steel.
基金supported by the U.S.Army Research Laboratory through their award#W911NF-22-2-0040the Ministry of Education,Youth and Sports of the Czech Republic through the e-INFRA CZ(ID:90254).
文摘Designing high-performance high-entropy alloys(HEAs)with transformation-induced plasticity(TRIP)or twinning-induced plasticity(TWIP)effects requires precise control over stacking fault energy(SFE)and phase stability.However,the vast complexity of multicomponent systems poses a major challenge for identifying promising candidates through conventional experimental or computational methods.A high-throughput CALPHAD framework is developed to identify compositions with potential TWIP/TRIP behaviors in the Cr-Co-Ni and Cr-Co-Ni-Fe systems through systematic screening of stacking fault energy(SFE),FCC phase stability,and FCC-to-HCP transition temperatures(T0).The approach combines TC-Python automation with parallel Gibbs energy calculations across hundreds of thousands of compositions,enabling efficient extraction of metastable FCC-dominant alloys.The high-throughput results find 214 compositions with desired properties from 160,000 candidates.Detailed analysis of the Gibbs energy distributions,phase fraction trends,and temperature-dependent SFE evolution reveals critical insights into the thermodynamic landscape governing plasticity mechanisms in HEAs.The results show that only a narrow region of the compositional space satisfies all screening criteria,emphasizing the necessity of an integrated approach.The screened compositions and trends provide a foundation for targeted experimental validation.Furthermore,this work demonstrates a scalable,composition-resolved strategy for predicting deformation mechanisms in multicomponent alloys and offers a blueprint for integrating thermodynamic screening with mechanistic understanding in HEA design.
基金funded by the National Natural Science Foundation of China(Nos.92266206,52227810)Jilin Province Science and Technology Development Plan(No.YDZJ202101ZYTS129)the Fundamental Research Funds for the Central Universities(No.2022-JCXK-11).
文摘Graphene(Gr)reinforced high-entropy alloy(HEA)matrix composites are expected as potential candidates for next-generation structural applications in light of outstanding mechanical properties.A deep comprehension of the underlying deformation mechanisms under extreme shock loading is of paramount importance,however,remains lacking due to experimentally technical limitations in existence.In the present study,by means of nonequilibrium molecular dynamics simulations,dynamic deformation behaviors and corresponding mechanisms in equiatomic FeNiCrCoCu HEA/Gr composite systems were investigated in terms of various shock velocities.The resistance to dislocation propagation imparted by Gr was corroborated to encourage the elevated local stress level by increasing the likelihood of dislocation interplays,which facilitated the onset of twins and hexagonal close-packed(HCP)martensite laths.Meanwhile,the advent of Gr was demonstrated to endow the HEA with an additional twinning pathway that induced a structural conversion from HCP to parent face-centered cubic(FCC)inside HCP martensite laths,different from the classical one that necessitated undergoing the intermediate procedure of extrinsic stacking fault(ESF)evolution.More than that,by virtue of an increase in flow stress,the transformation-induced plasticity(TRIP)effect was validated to be additionally evoked as the predominant strain accommodation mechanism at higher strains on the one hand,but which only assisted plasticity in pure systems,and on the other hand,can also act as an auxiliary regulation mode together with the twinning-induced plasticity(TWIP)effect under intermediate strains,but with enhanced contributions relative to pure systems.One may expect that TRIP and TWIP effects promoted by introducing Gr would considerably inspire a synergistic effect between strength and ductility,contributing to the exceptional shock-resistant performance of FeNiCrCoCu HEAs under extreme regimes.
基金the support of the French Agence Nationale de la Recherche(ANR),under grant ANR-21-CE08-0022(project ISANAMI)Junhui TANG is sponsored by the China Scholarship Council.
文摘This study proposes a novel strategy for the design of a new family of metastable Zr alloys.These al-loys offer improved mechanical properties for implants,particularly in applications where conventional stainless steels and Co-Cr alloys are currently used but lack suitability.The design approach is based on the controlled twinning-induced plasticity(TWIP)effect,significantly enhancing the ductility and strain-hardenability of the Zr alloys.In order to draw a“blueprint”for the compositional design of biomedical T WIP(Bio-T WIP)Zr alloys-using only non-toxic elements,the study combines D-electron phase stability calculations(specifically bond order(Bo)and mean d-orbital energy(Md))with a systematic experimental screening of active deformation mechanisms within the Zr-Nb-Sn alloy system.This research aids in ac-curately identifying the TWIP line,which signifies the mechanism shift between TWIP and classic slip as the primary deformation mechanism.To demonstrate the efficacy of the TWIP mechanism in enhancing mechanical properties,Zr-12Nb-2Sn,Zr-13Nb-1Sn,and Zr-14Nb-3Sn alloys are selected.Results indicate that the TWIP mechanism leads to a significant improvement of strain-hardening rate and a uniform elongation of∼20%in Zr-12Nb-2Sn,which displays both{332}<113>mechanical twinning and disloca-tion slip as the primary deformation mechanisms.Conversely,Zr-14Nb-3Sn exhibits the typical mechan-ical properties found in stable body-centered cubic(BCC)alloys,characterized by the sole occurrence of dislocation slip.Cell viability tests confirm the superior biocompatibility of Zr-Nb-based alloys with deformation twins on the surface,in line with existing literature.Based on the whole set of results,a comprehensive design diagram is proposed.
