Materials Science and Engineering: A最新文献_第10页

Solubility-dependent role of Ni in precipitation and thermal stability of Al–Mg–Si alloys Ni在Al-Mg-Si合金析出和热稳定性中的溶解度依赖作用

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-24 DOI: 10.1016/j.msea.2025.149679

Su-Min Nam , Kwangjun Euh , Myung Sik Choi , Hyeon-Woo Son

This study investigates the role of Ni addition on the precipitation behavior of Al-Mg-Si alloys, with particular emphasis on the solubility of trace elements during artificial aging. Comparative experiments were performed on a Base alloy (Al-0.73Mg-0.42Si, wt.%) and a Ni-added alloy (Al-0.73Mg-0.42Si-0.11Ni, wt.%) subjected to aging at 200 °C and 260 °C. The results reveal that Ni addition significantly enhances the age-hardening response by refining βʺ precipitates, which is primarily attributed to heterogeneous nucleation of Si clusters at Ni-rich clusters, regardless of aging temperature. Whereas at 260 °C, Ni segregation at the βʺ and βʹ precipitate interfaces becomes more pronounced, contributing to improved thermal stability during over-aging. Ni exhibits solute partitioning behavior similar to Cu forming sub-unit structure at the low-density cylinder structure of βʺ and

{(1 \overline{3} 0)}_{Al}

or

{(010)}_{Al}

habit planes of βʹ. However, unlike Cu, Ni is ultimately expelled as a pure phase during prolonged over-aging, which is presumed to be because Ni cannot be stabilized by forming quaternary precipitates such as C or Qʹ phases. Atom probe tomography demonstrates that the ratio between two different solute states of Ni is dependent on solubility at the aging temperature, and this mainly determines how many Ni solutes contributes to solute segregation at the matrix/precipitate boundary of βʺ and βʹ. These results emphasize the importance of solubility at the aging temperature in governing the role of low-solubility trace elements and suggest that Ni provides a unique alternative to Cu for tailoring precipitation pathways in Al-Mg-Si alloys.

本文研究了Ni对Al-Mg-Si合金析出行为的影响，重点研究了人工时效过程中微量元素的溶解度。分别对基体合金（Al-0.73Mg-0.42Si, wt.%）和添加ni合金（Al-0.73Mg-0.42Si-0.11 ni, wt.%）进行200℃和260℃时效对比实验。结果表明，Ni的加入通过细化β′′相显著增强了时效硬化响应，这主要是由于Si团簇在富Ni团簇处的非均相成核，而与时效温度无关。而在260℃时，Ni在β′和β′析出界面的偏析变得更加明显，有助于提高过时效过程中的热稳定性。Ni表现出与Cu相似的溶质分配行为，在β′的低密度圆柱形结构和（13′0）Al或（010）Al习惯面上形成亚基结构。然而，与Cu不同的是，Ni在长时间的过时效过程中最终以纯相的形式排出，这可能是因为Ni不能通过形成C相或Q′相等第四相来稳定。原子探针层析成像表明，Ni两种不同溶质态之间的比值取决于时效温度下的溶解度，这主要决定了Ni溶质的多少对β′和β′基体/析出界溶质偏析的影响。这些结果强调了时效温度下溶解度对控制低溶解度微量元素的作用的重要性，并表明Ni为定制Al-Mg-Si合金中的沉淀路径提供了独特的替代Cu。

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引用次数: 0

Preparation and research of AlCoCrFeNi / AZ31 composite materials by APS combined with FSP APS结合FSP制备AlCoCrFeNi / AZ31复合材料的研究

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-24 DOI: 10.1016/j.msea.2025.149674

Jinxin Liu , Wenbiao Gong , Yupeng Li , Shicheng Sun , Zhiyang Zhou , Xiang Yu , Wenxuan Liu , Yao Wang

In this work, an innovative combined approach is proposed, in which atmospheric plasma spraying (APS) is coupled with friction stir processing (FSP) to manufacture AZ31 magnesium-based composites containing high-entropy alloy (HEA) particle reinforcements at volume fractions ranging from 0 to 15 % in 5 % intervals, addressing the key limitations of traditional slot filling or drilling techniques (such as particle agglomeration and matrix weakening, etc.). The APS process can uniformly deposit HEA particles into coatings with controllable thicknesses (100 μm, 200 μm, 300 μm), ensuring uniform pre-distribution of the reinforcement material and suitability for complex geometries and thin-walled components. After FSP treatment, HEA particles retain their chemical integrity, forming a solute-rich transition zone through mutual diffusion with the substrate (approximately 0.6 μm), without undergoing chemical reactions to form brittle intermetallic compounds (IMCs). The homogeneous distribution of submicron-scale HEA particle fragments markedly enhanced dynamic recrystallization (DRX), leading to pronounced grain refinement within the composite. The experimental results revealed that, as the content of HEA particles increased to 15 vol%, the ultimate tensile strength (UTS), hardness, and yield strength (YS) of the composite improved significantly, rising from 87.2 HV, 126 MPa, and 237 MPa for the unreinforced alloy to 112.2 HV, 203 MPa, and 307 MPa, respectively. Fractographic observations indicated that ductile fracture predominated. This APS-FSP hybrid strategy demonstrates high automation potential in the large-scale production of high-performance magnesium-based composites.

在这项工作中，提出了一种创新的组合方法，其中大气等离子喷涂（APS）与搅拌摩擦加工（FSP）相结合，以5%的间隔以0 ~ 15%的体积分数制备含有高熵合金（HEA）颗粒增强的AZ31镁基复合材料，解决了传统槽填充或钻孔技术的关键局限性（如颗粒团聚和基体弱化等）。APS工艺可以将HEA颗粒均匀沉积到厚度可控（100 μm, 200 μm, 300 μm）的涂层中，确保增强材料的均匀预分布，并适用于复杂几何形状和薄壁部件。经过FSP处理后，HEA颗粒保持其化学完整性，通过与衬底相互扩散形成富溶质过渡区（约0.6 μm），而没有发生化学反应形成脆性金属间化合物（IMCs）。亚微米尺度HEA颗粒碎片的均匀分布显著增强了动态再结晶（DRX），导致复合材料内部晶粒细化。实验结果表明，当HEA颗粒含量增加到15 vol%时，复合材料的极限抗拉强度（UTS）、硬度和屈服强度（YS）显著提高，未增强合金的极限抗拉强度（UTS）、硬度和屈服强度（YS）分别从87.2 HV、126 MPa和237 MPa提高到112.2 HV、203 MPa和307 MPa。断口观察表明，断裂以韧性断裂为主。这种APS-FSP混合策略在高性能镁基复合材料的大规模生产中具有很高的自动化潜力。

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引用次数: 0

Multistage phase transitions achieve cryogenic reverse toughening in BCC structural multi-principal element alloys BCC结构多主元素合金的多级相变实现了低温逆增韧

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-24 DOI: 10.1016/j.msea.2025.149677

Xuehui Yan , Yong Zhang , Fanlu Hao , Haochen Qiu , Wei Jiang , Shuaishuai Wu , Shengli Guo , Baohong Zhu

One of the most formidable challenges confronting cryogenic structural materials is the substantial loss of plasticity at low temperatures. In this study, we unveil a distinctive cryogenic reverse toughening behavior in a non-equiatomic Zr₅₀Ti₃₅Nb₁₅ multi-principal element alloy (MPEA), characterized by a pronounced increase in both plasticity and strength. As the temperature decreases from 273 K to 77 K, the yield strength of the alloy escalates from 725 MPa to 1422 MPa, while the ductility improves from 12.5 % to 18.8 %. We have observed that a sequentially activated multistage phase transition mechanism serves as the key to enhancing cryogenic strength and ductility together. Specifically, the transformation progresses from the body-centered cubic (BCC) structure to stress-induced orthorhombic structural martensite (BCC → SIM-α″) and hexagonal structural martensite (BCC → SIM-α′). Furthermore, the activation of stress-induced nano-twinning within the SIM-α″ phase confers exceptional crack-arresting ability and damage tolerance during deformation at 77 K (SIM-α″ → nano-twinning). The results indicate that microstructure manipulation to trigger synergistic strengthening mechanisms opens a new avenue for developing next-generation cryogenic structural materials, offering a transformative way to improve their low-temperature performance.

低温结构材料面临的最严峻的挑战之一是在低温下塑性的大量损失。在这项研究中，我们揭示了非等原子Zr50Ti35Nb15多主元素合金（MPEA）独特的低温反向增韧行为，其特点是塑性和强度都显著提高。当温度从273 K降低到77 K时，合金的屈服强度从725 MPa上升到1422 MPa，塑性从12.5%提高到18.8%。我们观察到，顺序激活的多阶段相变机制是同时提高低温强度和塑性的关键。具体来说，从体心立方（BCC）结构转变为应力诱导的正交结构马氏体（BCC→SIM-α″）和六边形结构马氏体（BCC→SIM-α′）。此外，SIM-α″相内的应力诱导纳米孪晶的激活赋予了在77 K变形时优异的裂纹止裂能力和损伤容忍度（SIM-α″→纳米孪晶）。研究结果表明，通过微观结构调控触发协同强化机制，为开发下一代低温结构材料开辟了新的途径，为改善其低温性能提供了一种变革性的方法。

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引用次数: 0

Fabrication-dependent hydrogen embrittlement of Ti6Al4V alloy at 15 K Ti6Al4V合金在15k时的氢脆

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-24 DOI: 10.1016/j.msea.2025.149678

Tien-Dung Nguyen, Taeho Lee, Keun Hyung Lee, Thanh-Dat Nguyen, Dong-Hyun Lee, Soo Yeol Lee

This study focused on how fabrication-induced microstructures affect the ultra-cryogenic deformation and hydrogen embrittlement behavior of Ti6Al4V alloys produced by directed energy deposition, hot rolling, and tungsten inert gas welding for aerospace applications. Electrochemical hydrogen charging was performed at room temperature, followed by tensile testing at 15 K. Distinct microstructure-governed distributions of TiH₂ and hydrogen influenced fracture behavior. The hot-rolled alloy exhibited the highest hydrogen embrittlement resistance, while the other alloys showed increased susceptibility to hydrogen-assisted cracking due to greater hydrogen uptake and deeper hydrogen-affected regions.

本研究重点研究了航空航天用定向能沉积、热轧和钨惰性气焊制备的Ti6Al4V合金的制备诱导显微组织对其超低温变形和氢脆行为的影响。在室温下进行电化学充氢，然后在15k下进行拉伸试验。TiH2和氢的不同微观组织分布影响断裂行为。热轧合金表现出最高的抗氢脆性，而其他合金由于更大的氢吸收和更深的氢影响区而表现出对氢辅助开裂的敏感性。

引用次数: 0

Chemical heterogeneity enhances very high cycle fatigue resistance of carbide-free bainitic steel 化学非均质性使无碳化物贝氏体钢具有很高的抗循环疲劳性能

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-24 DOI: 10.1016/j.msea.2025.149667

Xiaolu Gui , Kun Wang , Miao Liu , Zongyan Liu , Zhiping Xiong , Chun Feng , Guhui Gao

In this study, we investigated the very-high-cycle fatigue (VHCF) behavior of high-carbon bainitic steel with and without chemical heterogeneity. The only processing difference was the initial microstructure: pearlite for chemically heterogeneous steel (PUB-320) versus martensite for homogeneous steel (MUB-320), with all subsequent steps being identical, including fast heating and bainitic austempering. The heterogeneous steel exhibited an ultrafine bainitic structure characterized by Mn-enriched film-like retained austenite (RA) and Mn-depleted bainitic ferrite. A significant enhancement in the VHCF strength (σ_w9, at 10⁹ cycles) was achieved, increasing from 728 MPa (MUB-320) to 812 MPa (PUB-320), corresponding to a fatigue strength ratio (σ_w9/UTS) of 0.52. This enhancement is directly attributed to the chemical heterogeneity, which improves the mechanical stability of RA and modifies its plastic deformation mechanisms. Under cyclic loading, the RA ahead of the microcracks either remains stable or transforms into stacking faults, mechanical twins, or nano-sized martensite, thereby alleviating the local stress concentrations and impeding microcrack propagation. These findings underscore the potential of chemical heterogeneity as an effective microstructural strategy for enhancing the fatigue resistance of bainitic steels without requiring costly ultra-clean steelmaking processes.

在本研究中，我们研究了具有和不具有化学非均质性的高碳贝氏体钢的甚高周疲劳（VHCF）行为。唯一的加工区别是初始组织：化学非均质钢（PUB-320）的珠光体与均匀钢（MUB-320）的马氏体，所有后续步骤都是相同的，包括快速加热和贝氏体等温回火。非均质钢表现为富锰膜状残余奥氏体（RA）和贫锰贝氏体铁素体的超细贝氏体结构。VHCF强度（σw9，在109次循环时）得到显著提高，从728 MPa （MUB-320）增加到812 MPa (PUB-320)，对应的疲劳强度比（σw9/UTS）为0.52。这种增强直接归因于化学非均质性，它提高了RA的机械稳定性并改变了其塑性变形机制。在循环载荷作用下，微裂纹前面的RA要么保持稳定，要么转变为层错、机械孪晶或纳米马氏体，从而减轻了局部应力集中，阻碍了微裂纹的扩展。这些发现强调了化学非均质性作为一种有效的显微组织策略的潜力，可以提高贝氏体钢的抗疲劳性，而不需要昂贵的超清洁炼钢工艺。

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引用次数: 0

Microstructure-guided design of single-phase refractory high-entropy alloys via competing chemical short-range orders 基于竞争化学短程指令的单相难熔高熵合金微结构导向设计

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-24 DOI: 10.1016/j.msea.2025.149675

Jiacheng Sun , Longchao Zhuo , Shujie Pang , Wenlong Xiao , Huyang Li , Guan Wang , Yuanhong Liu , Peter K. Liaw , Tao Zhang

Refractory high-entropy alloys (RHEAs) exhibit exceptional high-temperature strengths but tend to suffer from limited room-temperature ductility, particularly in aluminum-containing systems where brittle intermetallic precipitation degrades mechanical properties. Here we developed a Monte Carlo (MC)/molecular dynamics (MD) framework to engineer chemical short-range order for single-phase design. Starting from the Al₂TiZrHfNbTa with a dual phase structure, MC/MD iterations for decreasing system energy yielded an optimized composition of Al₂₂.₅Ti₁₁.₇Zr₁₃.₂Hf₁₅.₃Nb₁₈.₂Ta₁₉.₁. The optimized alloy achieved a single B2 phase with enhanced Al-Ti/Al-Zr clustering and reduced Ta segregation. Experimental validation confirmed the property improvements, including the improvement of yield strength from 1389.4 MPa to 1465.7 MPa, ultimate compressive strength from 1416.8 MPa to 1615.8 MPa, and fracture strain from 2.8 % to 7.5 %, which can be attributed to earlier dislocation nucleation and sustained higher dislocation density throughout deformation. This computational framework establishes rational pathways for designing RHEAs by directly linking atomic-scale chemical ordering to phase stability and mechanical performance.

耐火高熵合金（RHEAs）表现出优异的高温强度，但室温延展性有限，特别是在含铝系统中，脆性金属间析出会降低机械性能。在这里，我们开发了一个蒙特卡罗(MC)/分子动力学（MD）框架来设计单相设计的化学短程顺序。从双相结构的Al2TiZrHfNbTa开始，MC/MD迭代降低体系能量，得到了Al22.5Ti11.7Zr13.2Hf15.3Nb18.2Ta19.1的优化组合。优化后的合金获得了单一的B2相，增强了Al-Ti/Al-Zr聚类，减少了Ta偏析。实验验证表明：屈服强度从1389.4 MPa提高到1465.7 MPa，极限抗压强度从1416.8 MPa提高到1615.8 MPa，断裂应变从2.8%提高到7.5%，这是由于变形过程中位错形核提前，位错密度持续提高所致。该计算框架通过将原子尺度的化学有序与相稳定性和力学性能直接联系起来，为设计RHEAs建立了合理的途径。

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引用次数: 0

Enhanced strength-ductility synergy in a low-density, low-Co γ′ strengthened medium entropy alloys 低密度、低co γ′强化中熵合金增强的强度-塑性协同效应

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-23 DOI: 10.1016/j.msea.2025.149660

Sujatha Desetti , M. Nagini , D. Arvindha Babu , Dova Kalyan , Surendra Kumar Makineni , Sai Rama Krishna Malladi , B.S. Murty

Designing lightweight, high-strength alloys with excellent ductility is paramount for next-generation high-temperature structural applications. In this study, a series of low-density, low-Co (9.5 at. %) γ′ strengthened Ni-based medium entropy alloys (MEAs) with systematically varying Al and Ti content (5–7 at. %) (Al + Ti content from 10 to 14 at. %) were designed and developed for turbine disk applications. These MEAs exhibit a duplex microstructure with finely dispersed L1₂-ordered precipitates (γ′) within a face-centered-cubic (FCC) matrix (γ). Atomic-scale compositional analysis unveiled distinct elemental partitioning, with Ni, Al, and Ti strongly partitioning to the γ′, while Co and Cr preferentially partition to the γ matrix. The optimized MEA (7 at. % Al and Ti) achieves outstanding room temperature mechanical properties: yield strength 929 ± 5 MPa, ultimate tensile strength 1272 ± 24 MPa, and ductility 14.2 ± 2 %, with a low density of 7.54 g cm⁻³ and a negative lattice misfit of 0.4 %. The corresponding specific strength is 123 MPa g⁻¹ cm⁻³ markedly exceeds that of state-of-the-art wrought Ni-based superalloys such as Waspaloy (97 MPa g⁻¹ cm⁻³), presenting a cost-effective, low-density alternative for next-generation turbine disk applications. Strengthening is primarily attributed to nanoprecipitation hardening, contributing ∼57 % of the total yield strength, with operative deformation mechanisms including precipitate shearing and Orowan looping. TEM reveals dislocation-precipitate interactions consistent with these deformation mechanisms. Fractography reveals a mixed mode of fracture, with cracks initiating at interdendritic eutectic phases. This study presents an effective alloy design strategy for developing cost-effective, low-density γ′ strengthened MEAs with enhanced tensile properties.

设计具有优异延展性的轻质、高强度合金对于下一代高温结构应用至关重要。在这项研究中，一系列低密度，低co (9.5 at。%) γ′强化镍基中熵合金（MEAs）具有系统变化的Al和Ti含量（5-7 at）。%) (Al + Ti含量从10 ~ 14 at。%)的设计和开发的涡轮盘应用。这些MEAs表现为双相结构，在面心立方（FCC）基体（γ）中具有分散的l12有序相（γ′）。原子尺度的成分分析揭示了明显的元素分配，Ni、Al和Ti强烈分配到γ′，而Co和Cr优先分配到γ′。优化后的MEA (7 at。% Al和Ti)具有优异的室温力学性能：屈服强度为929±5 MPa，极限抗拉强度为1272±24 MPa，延展性为14.2±2%，低密度为7.54 g cm−3，负晶格失配率为0.4%。相应的比强度为123 MPa g−1 cm−3，明显超过了最先进的锻造镍基高温合金，如Waspaloy (97 MPa g−1 cm−3)，为下一代涡轮盘应用提供了一种经济高效、低密度的替代方案。强化主要归因于纳米沉淀硬化，占总屈服强度的57%，有效的变形机制包括沉淀剪切和Orowan环。透射电镜显示了与这些变形机制一致的位错-沉淀相互作用。断口形貌显示为混合断裂模式，裂纹起源于枝晶间共晶相。本研究提出了一种有效的合金设计策略，用于开发具有增强拉伸性能的低密度γ′强化mea。

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引用次数: 0

Tailoring strength-ductility synergy in laser directed energy deposited Ni-rich high-entropy alloys through hierarchical precipitation strategy 分层沉淀法在激光定向能沉积富镍高熵合金中的强度-延性协同作用

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-23 DOI: 10.1016/j.msea.2025.149670

Hao Liu , Bin Wang , Peijian Chen , Binxin Dong , Yu Fan , Yanhua Bian , Qiansheng Xu , Gang Yu , Xiuli He

This study uses phase diagram calculations for design and employs laser directed energy deposition (LDED) technique to fabricated Ni_3x(FeCr)_yCo_(x + y)/2 (x/y = 0.5, 0.75, 1.0, 1.5) high-entropy alloys (HEAs) with FCC-structured γ phase as the primary phase. A sequential thermal treatment schedule comprising solution treatment followed by aging is employed to regulate the multistage precipitation behavior of the coherently grown L1₂-structured γ′ phase and incoherent HCP-structured Laves phase. The results show that with increasing x/y ratio, the content of the brittle Laves phase in the HEAs decreases, and its morphology evolves from blocky to chain-like and particle-like forms. This transformation contributes to a trend of decreasing strength but increasing ductility. After solid-solution treatment, partial dissolution of the Laves phase is observed, resulting in improved ductility but reduced yield strength. Subsequent aged treatment induces the precipitation of a high density of coherent γ′ nanoparticles, significantly enhancing the yield strength of the HEAs. Notably, the aged alloy with x/y = 1.5 exhibits outstanding mechanical properties, achieving a yield strength of 1074 MPa along the scanning direction (SD), which is a 107 % improvement compared to its solution-treated counterpart, while retaining a high elongation of 23 %. The superior strength–ductility synergy is primarily attributed to the hierarchical precipitation strengthening effect of coherent γ′ nanoparticles formed during aging and the residual incoherent Laves phase retained after solution treatment. This work provides valuable guidance for the design and fabrication of HEAs thin-walled structures with strength-ductility synergy using LDED.

本研究利用相图计算进行设计，采用激光定向能沉积（LDED）技术制备了以fcc结构γ相为初相的Ni3x(FeCr)yCo(x + y)/2 （x/y = 0.5, 0.75, 1.0, 1.5）高熵合金（HEAs）。采用固溶后时效的顺序热处理方案，调节了l12结构的共长型γ′相和hcp结构的非共长型Laves相的多级析出行为。结果表明：随着x/y比值的增大，HEAs中脆性Laves相含量减少，其形态由块状演变为链状和颗粒状；这种转变导致了强度下降而延性增加的趋势。固溶处理后，观察到Laves相的部分溶解，导致延展性提高，但屈服强度降低。随后的时效处理诱导出高密度的相干γ纳米颗粒，显著提高了HEAs的屈服强度。值得注意的是，x/y = 1.5时效合金表现出优异的力学性能，沿扫描方向（SD）的屈服强度达到1074 MPa，与固溶处理合金相比提高了107%，同时保持了23%的高伸长率。这种优异的强度-延性协同作用主要归因于时效过程中形成的共格γ′纳米颗粒的分层沉淀强化作用以及固溶处理后残留的非共格Laves相。本文的工作为利用led设计和制造具有强度-延性协同作用的HEAs薄壁结构提供了有价值的指导。

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引用次数: 0

Abnormal reduction in work-hardening rate of Cr4Mo4Ni4V martensitic steel induced by interface carbides suppressing boundary sliding 界面碳化物抑制边界滑动导致Cr4Mo4Ni4V马氏体钢加工硬化率异常降低

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-23 DOI: 10.1016/j.msea.2025.149664

Wanli Yang , Bin Shao , Hongwei Jiang , Haonan Zou , Shengchang Yan , Yujie Ma , Wei Tang , Pengwen Zhou , Yingying Zong

Lath martensitic steels are widely used for their excellent mechanical properties. In this study, we aim to understand how microstructural features affect plastic deformation mechanisms and mechanical responses. While second-phase particles such as carbides are generally believed to enhance strength and work hardening through dislocation obstruction, we found that film-like carbides distributed along substructure boundaries suppress boundary sliding and result in an unusual mechanical response: increased yield strength but decreased tensile strength and work hardening rate. This deviation from conventional expectations is attributed to a shift in deformation mechanism. When boundary sliding is suppressed by the presence of film-like carbides, deformation is dominated by dislocation slip within laths. However, the lack of interfacial plasticity leads to stress localization and dislocation accumulation, limiting further hardening. These findings reveal a distinct mechanism–property correlation in lath martensite and suggest a new approach to tailoring mechanical behavior through interfacial design.

板条马氏体钢因其优异的力学性能而得到广泛应用。在本研究中，我们旨在了解微观结构特征如何影响塑性变形机制和力学响应。通常认为，第二相颗粒（如碳化物）通过位错阻碍提高了强度和加工硬化，但我们发现沿亚结构边界分布的薄膜状碳化物抑制了边界滑动，并导致了不寻常的机械响应：屈服强度增加，但拉伸强度和加工硬化速率降低。这种与传统预期的偏离归因于变形机制的转变。当层状碳化物的存在抑制了边界滑动时，变形主要是由位错滑移引起的。然而，界面塑性的缺乏导致应力局部化和位错积累，限制了进一步硬化。这些发现揭示了板条马氏体中明显的机制-性能相关性，并提出了一种通过界面设计来剪裁力学行为的新方法。

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引用次数: 0

High-temperature deformation mechanisms in a high-Nb TiAl alloy fabricated by laser metal deposition 激光金属沉积制备高铌TiAl合金的高温变形机理

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-23 DOI: 10.1016/j.msea.2025.149673

Leyu Cai , Kai Huang , Shiqiu Liu , Zengbao Jiao , Qingge Wang , Ian Baker , Hong Wu

TiAl alloys possess excellent properties, including low density and excellent oxidation and creep resistance at high temperatures, making them highly valuable for aerospace applications, particularly in aero-engine turbine blades. Laser metal deposition (LMD) has emerged as a promising technique to address the challenges associated with processing and forming TiAl alloys, while also offering the potential to enhance their high-temperature performance. In this study, a high-Nb TiAl alloy with a nearly γ microstructure was prepared using LMD. The resulting microstructure exhibits significant heterogeneity, comprising fine γ lamellae, coarse γ phases, β₀ bands, and metastable L1₂ precipitates. The alloy achieved an ultimate tensile strength of 728 ± 19 MPa at 700 °C, which decreased slightly to 714 ± 15 MPa at 800 °C, while the elongation to failure increased from 8.7 ± 0.8 % at 700 °C to 12.6 ± 1.2 % at 800 °C. The dominant high-temperature deformation mechanisms include dislocation slip in the fine γ lamellae, deformation twinning in the coarse γ phase, dislocation accumulation in β₀ bands, and strain accommodation via the L1₂ phase. This work deepens the understanding of the high-temperature deformation mechanisms of LMDed high-Nb TiAl alloy.

TiAl合金具有优异的性能，包括低密度和高温下优异的抗氧化和抗蠕变性能，使其在航空航天应用中具有很高的价值，特别是在航空发动机涡轮叶片中。激光金属沉积（LMD）已经成为一种有前途的技术，可以解决与加工和成形TiAl合金相关的挑战，同时也提供了增强其高温性能的潜力。本研究采用LMD法制备了近γ显微组织的高nb TiAl合金。显微结构表现出明显的非均匀性，包括细小的γ片层、粗的γ相、β0带和亚稳的L12相。合金在700℃的极限抗拉强度为728±19 MPa，在800℃的极限抗拉强度为714±15 MPa，而断裂伸长率从700℃的8.7±0.8%上升到800℃的12.6±1.2%。主要的高温变形机制包括γ细片的位错滑移、γ粗相的变形孪晶、β0带的位错积累和L12相的应变调节。本工作加深了对LMDed高铌TiAl合金高温变形机理的认识。

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引用次数: 0