Ni-Cr-W三元系富Ni侧fcc相的互扩散及原子迁移率参数研究

利用电子探针微量分析与Whittle-Green方法确定了在1200℃下退火72 h的Ni-Cr-W三元合金体系的互扩散系数。通过DICTRA软件包对实验互扩散系数进行评估以确定原子迁移率。通过全面分析比较模型预测的扩散特性和实验数据的良好一致性验证了原子迁移率的合理性。Ni-Cr-W三元体系中的扩散现象,如扩散路径和浓度-距离曲线可以通过获得的原子迁移率合理地描述,进一步证明了本研究所获得的原子迁移率参数的可靠性。     

Ni-Nb-Ti三元系富Ni侧fcc相的互扩散及原子迁移率参数研究

本研究利用EPMA技术测定了Ni-Nb-Ti三元系富Ni侧合金在1000℃下的扩散数据,并使用Whittle and Green方法计算了Ni-Nb-Ti三元系在1000℃下的互扩散系数。通过DICTRA软件优化得到Ni-Nb-Ti三元系的fcc相的原子迁移率参数,运用优化得到的的原子迁移率计算出的互扩散系数与实验数据具有较好的一致性,从而验证了所得的原子迁移率参数的可靠性。同时通过运用迁移率参数拟合各扩散偶的的浓度-距离曲线和扩散路径,进一步验证了参数的合理性。     

Ni-Cr-W三元系富Ni侧fcc相的互扩散及原子迁移率研究（英文）

利用电子探针微量分析与Whittle-Green方法确定了在1200℃下退火72 h的Ni-Cr-W三元合金体系的互扩散系数。通过DICTRA软件包对实验互扩散系数进行评估以确定原子迁移率。通过全面分析比较模型预测的扩散特性和实验数据的良好一致性验证了原子迁移率的合理性。Ni-Cr-W三元体系中的扩散现象,如扩散路径和浓度-距离曲线可以通过获得的原子迁移率合理地描述,进一步证明了本研究所获得的原子迁移率参数的可靠性。     

BCC Cr-x(x=Co,Si)二元体系的互扩散系数

为建立用于设计和开发NiCrAlCoSi系HEA粘结层的迁移率数据库,本研究分别用Cr-5.5％Co与Cr-4.5％Si(原子数分数)合金与纯铬制备了两组扩散偶,用电子探针获得成分-距离曲线,研究了其1423 K和1473 K的扩散行为.结果 表明,BCC Cr-x(x=Co,Si)二.元系的互扩散系数随温度的升高而增...     

Fe-Al-Si三元扩散偶中合金元素扩散行为的动力学计算

建立了Fe- 6.8%Al-1.0%Si/Fe和Fe-6.3%Al-0.9%Si/Fe两组扩散偶,分别对其进行1 050 ℃×3 h和1 000 ℃×64 h的退火处理,而后采用EPMA技术对合金元素在不同扩散偶中的成分分布进行测定;同时结合Fe-Al-Si体系的热力学与动力学性质,采用Thermo-Calc & DICTRA软件中的移动界面模型,对Fe、Al和Si元素随温度与时间的浓度变化情况进行了模拟计算,计算结果与实验测定的成分分布数据吻合得较好,从而验证了计算中所采用热力学与动力学参数的有效性,并可为模拟相关合金体系中相组成的演变行为提供计算依据.     

Ti-Mo二元合金在β相区的互扩散行为

将Ti-Mo纯金属组成扩散偶,在950～1 050℃间研究Ti-Mo二元合金在β相区的互扩散行为.利用电子探针(EPMA)测定Ti-Mo扩散偶在扩散区中Mo元素浓度,建立浓度变化曲线,根据浓度曲线用Den Broeder方法计算该扩散偶在β相区的互扩散系数,用Hall方法计算富Mo侧和富Ti侧的互扩散系数.结果表明:互扩散系数与浓度之间存在较强烈的依赖关系;杂质扩散系数可通过Vignes-Birchenall公式获得,并与Hall方法获得的结果进行比较,这两种方法得到的结果比较接近:采用Arrhenius方程获得不同浓度下的扩散激活能和频率因子,二者的峰值均出现在Mo摩尔浓度约为35%处.     

强磁场下Ni-Cu系原子的扩散行为

采用Cu/Ni/Cu扩散偶研究强磁场对Ni?Cu系原子扩散行为的影响。发现该扩散偶在有、无强磁场条件下退火处理时,Ni?Cu 系原子互扩散过程中的互扩散系数随着互扩散区内 Ni 原子摩尔分数的增加而增加,并且在强磁场条件下退火处理后,所有的互扩散系数均小于相应条件下无磁场处理时的互扩散系数。表明强磁场的施加延迟了Ni?Cu系原子的互扩散行为。分析指出,上述强磁场对原子扩散的延迟行为是通过降低互扩散过程中的频率因子而不是互扩散激活能来实现的。     

Co-Cr-Re三元体系FCC相的1373和1473 K扩散动力学研究

制备了8对Co-Cr-Re体系FCC相的扩散偶样品,采用电子探针X射线显微分析仪测量其成分-距离曲线,利用Whittle-Green方法获得互扩散系数。在评估并确定了该体系子二元系的原子移动性参数后,结合热力学数据库与互扩散系数试验数据,评估优化三元系的原子移动性参数。通过对比成分-距离曲线、扩散通道和主扩散系数的计算结果与试验数据,验证了Co-Cr-Re三元体系原子移动性参数的准确性。     

Ti-Zr二元合金在β相区的互扩散行为研究

通过扩散偶技术,利用电子探针(EPMA)研究了Ti-Zr二元合金在β相区(950至1150℃)的互扩散行为。采用Den Broeder方法及Hall修正法计算了Ti-Zr二元合金的互扩散系数,其范围为10-14～10-12m2/s;计算了扩散激活能Q和频率因子D0,两者均随Zr浓度的增加呈现先增加后减小的规律,其峰值均出现在50at%Zr浓度附近。用Vignes-Birchenall方法计算了Ti-Zr二元合金在扩散组元极限浓度处的杂质扩散系数,并与用Hall修正方法计算的互扩散系数进行了对比,二者结果比较接近。     

难熔多组元Ti-Nb-Zr-W合金随成分变化弹塑性和扩散性能的高通量探索（英文）

组合材料合成和分析方法能够很好地描述Ti-Nb-Zr-W体系难熔多元合金的弹塑性和扩散特性。在1273 K温度固溶退火25 h后制备6组Ti-Nb-Zr-W四元扩散偶,并对其开展电子探针显微分析和纳米压痕测试。随后,采用Oliver-Pharr和反向分析算法等方法获得Ti-Nb-Zr-W体系宽广成分范围的随成分变化弹塑性。此外,采用机器学习和实用高效数值回归方法分别建立Ti-Nb-Zr-W体系体心立方相的弹塑性和互扩散系数数据库。同时,提出由杨氏模量与主互扩散系数之比所定义的热加工性能参数来评估热加工过程行为。最后,讨论难熔多元合金的耐磨性并进行实验验证。结果表明,低钨含量的富Ti难熔多元合金具有高硬度、良好的耐磨性、高应力和良好的热加工性能,而高钨含量并不能改善富Ti难熔合金的弹塑性。     

Interdiffusion and Atomic Mobilities in fcc Co-Ga and Co-V Alloys

On the basis of Co/Co-10Ga, Co/Co-12Ga, and Co/Co-10V (at.%) diffusion couples, interdiffusion coefficients in the face-centered cubic (fcc) phase of the Co-Ga and Co-V binary systems were investigated in the temperature range between 1273 and 1573 K by means of the den Broeder method. Based on available thermodynamic information, the interdiffusion data were assessed to develop the atomic mobilities for the fcc Co-Ga and Co-V alloys using the DICTRA software package, and their validity was tested by simulating concentration–distance profiles.     

Interdiffusion and Atomic Mobilities of fcc Co-V-Mo Alloys: Measurement and Modeling

Based on 18 bulk diffusion couples, the composition-dependent interdiffusion coefficients in the fcc Co-V-Mo alloys at 1273, 1373 and 1473 K were obtained from the intersection points of the diffusion couples by means of EPMA technique coupled with the Whittle and Green method. With the experimentally determined interdiffusion coefficients and the critically reviewed experimental diffusivities available in the literature, the atomic mobilities of fcc Co-V-Mo alloys were assessed by means of Diffusion Controlled Transformation (DICTRA) software. The quality of the assessed atomic mobilities was confirmed by the comprehensive comparisons between various DICTRA-calculated diffusion behaviors and the experimental ones, including concentration profiles and diffusion paths.     

Assessment and Evaluation of Mobilities for Diffusion in the bcc Cr-V-Fe System

Assessments of diffusion mobility parameters are performed for the bcc Cr-V-Fe alloy system by taking available literature data into account. The main focus is on the diffusion of V in the bcc phase where, in addition to all binaries, ternary interaction parameters are assessed. An experiment is performed in order to study the coarsening of V-rich MC carbide, where the diffusion of V is believed to be of major importance. The measured coarsening rate is compared with the rate calculated using DICTRA, and found to be in satisfactory agreement. The aspects of coarsening experiments as a method to evaluate diffusion mobility data are discussed.     

Diffusion and Atomic Mobilities in fcc Ni-Sn Alloys

The composition-distance profiles in face-centered cubic (fcc) Ni-Sn alloys at 1173, 1223, 1273, and 1323 K were measured by means of electronic probe microanalysis (EPMA) using Ni/Ni-7.3at.%Sn diffusion couples. Based on the available thermodynamic information and various experimental diffusion coefficients, the atomic mobilities of Ni and Sn in fcc Ni-Sn alloys were assessed as a function of temperature and composition in terms of the CALPHAD method using the DICTRA^® software package. Optimized mobility parameters are presented. Comparisons between the calculated and measured diffusion coefficients show that most of the experimental information can be reproduced reasonably. The obtained mobility parameters can also predict satisfactorily the composition-distance profiles of the Ni/Ni-7.3at.%Sn diffusion couples determined in the present work.     

Atomic Mobilities and Diffusivities in fcc Co-Cr-Ti Alloys

In order to develop the atomic mobilities for the fcc phase of the Co-Cr-Ti alloys, interdiffusivities were determined with diffusion couples annealed at 1323 K for 100 h, the results of which were then critically assessed using the DICTRA software. From comprehensive comparisons between the calculated and the experimentally measured diffusion coefficients, good agreements can be obtained. The obtained atomic mobilities for fcc Co-Cr-Ti alloys are further verified through numerically simulated concentration profiles in diffusion couples, where the kinetic characteristics can be fully reproduced.     

Assessment of Atomic Mobilities in fcc Al-Ag-Zn Alloys

Based on various experimental diffusivities of fcc Al-Ag-Zn alloys available in the literature and the thermodynamic parameter evaluated in the present work, atomic mobilities of Al, Ag and Zn in the fcc Al-Ag-Zn system were assessed as a function of composition and temperature with the aid of DICTRA software. Comparison between the calculated diffusivities and the corresponding experimental data indicates that the presently obtained atomic mobilities can reproduce most of the diffusivities, such as tracer diffusivities, impurity diffusivities and interdiffusivities in both binary and ternary systems. The reliability of the atomic mobilities was further verified via comparisons between the model-predicted concentration-distance profiles of the binary and ternary diffusion couples and the experimentally measured ones. Good agreement between the calculated and the measured concentration-distance profiles indicates that the presently obtained atomic mobilities are reliable. The diffusion paths can be also reproduced by the presently obtained atomic mobilities.