Diffusion and its mechanism in B2-type ordered NiAl at high pressures.

B2型有序NiAl高压下的扩散及其机理

• 批准号: 09650717
• 负责人: MINAMINO Yoritoshi
• 金额: $ 2.5万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650717/
• 关键词: diffusion; NiAl phase; Intermetallic compound; high pressure; activation volume; B2-type ordered structure; activation energy; diffusion profile

The allays of NiAl, NiAl-Fe, NIAl-Ti and NiAl-Mn were prepared in order to make the diffusion couples of (NiAl/NiAl-Fe), (NiAl/NiAl-Ti) and (NiAl/NiAl-Mn).The diffusion profiles in the diffusion couples annealed at high pressures up to 3GPa were measured by an electron probe microanalyzer.The diffusion coefficients were determined from the diffusion profiles by Hall's method.The activation volumes, DELTAV_D, of diffusion in NiAl could be evaluated from the pressure dependence of diffusion coefficients by using the following equation ; *lnD/*P = -DELTAV_D / RT+ r_GK_T.The DELTAV_D is an important value and an effective information for understanding the diffusion mechanisms, because it indicates the physical amount corresponding to the defects which contribute to the diffusion in NiAl.The results of this research are as follows ; (1) DELTAV_D(m^3/mol) of Mn diffusion in NiAl at 1623K : 4.11x1O^<-6> at 43.6at%Al, 5.87x10^<-6> at 45.8at%Al, 6.70x10^<-6> at 47.5at%A1, 7.O8x1O^<-6> at 49.8at … More %Al, 3.1Ox1O^<-6> at 50.8at%Al and 2.49x10^<-6> at 51.3at%Al, (2) DELTAV_D of Fe diffusion in NiAl at 1548K : 3.27x10^<-6> at 44.3at%A1, 4.65x10^<-6> at 46.8at%A1, 5.50x10^<-6> 48.8at%Al, 6.06x10^<-6> at 49.5at%Al, 5.5Ox10^<-6> at 50.7at%Al and 3.24x10^<-6> at 51.4at%Al, (3) DELTAV_D of Ti diffusion in NiAl at 1598K : 5.54x10^<-6> at 44.Oat%Al, 6.O6x10^<-6> at 46.9at%Al, 7.71x10^<-6> at 49.7at%Al, 5.86x10^<-6> at 50.8at%Al and 3.lOx10^<-6> at 51.4at%Al.The DELTAV_D values have the maximum at the stoichiometric composition and they are (6.O-7.7) V_0, where the V_0 is the molar volume.This strongly means that the diffusion occurs by the complicated mechanism with the divacancies.In the Ni-rich side, the DELTAV_D decreases gradually with the Al composition.This indicates that the single vacancies contribute to the diffusion in addition to the divacancies.On the other hand, in the Al-rich side, the DELTAV_D decreases steeply with the Al composition.This reveals that diffusion occurs mainly under the activated process of migration because the structural Ni-vacancies contribute to diffusion and then the activated process of vacancy formation is not important.Thus, the diffusion mechanism in NiAl has been understood above. Less

制备了NiAl、NiAl-Fe、NIAl-Ti和NiAl-Mn合金，以形成(NiAl/NiAl-Fe)、(NiAl/NiAl-Ti)和(NiAl/NiAl-Mn)扩散对。通过电子探针显微分析仪测量了在高达3GPa的高压下退火的扩散对中的扩散曲线。扩散系数由下式确定： NiAl 中扩散的激活体积 DELTAV_D 可以通过使用以下方程根据扩散系数的压力依赖性进行评估； *lnD/*P = -DELTAV_D / RT+ r_GK_T。DELTAV_D 是理解扩散机制的重要值和有效信息，因为它表示与 NiAl 中有助于扩散的缺陷相对应的物理量。本研究结果如下； (1) 1623K时Mn在NiAl中扩散的DELTAV_D(m^3/mol)：43.6at%Al时4.11x1O^<-6>、45.8at%Al时5.87x10^<-6>、47.5at%Al时6.70x10^<-6>、7.O8x1O^<-6> 49.8at … 更多 %Al, 3.1Ox1O^<-6> at 50.8at%Al 和 51.3at%Al 时 2.49x10^<-6>，(2) 1548K 时 NiAl 中 Fe 扩散的 DELTAV_D：44.3at%A1 时 3.27x10^<-6>，46.8at%A1 时 4.65x10^<-6>，5.50x10^<-6> 48.8at%Al, 6.06x10^<-6> 在 49.5at%Al, 5.5Ox10^<-6> at 50.7at%Al 和 3.24x10^<-6> at 51.4at%Al, (3) Ti 在 NiAl 中扩散的 DELTAV_D (1598K): 5.54x10^-6> at 44.Oat%Al, 6.O6x10^-6> at 46.9at%Al, 7.71x10^<-6> 在 49.7at%Al、5.86x10^<-6> at 50.8at%Al和3.10x10^<-6> at 51.4at%Al。DELTAV_D值在化学计量组成处具有最大值，它们是(6.O-7.7)V_0，其中V_0是摩尔体积。这强烈意味着扩散是通过具有双空位的复杂机制发生的。的 富 Ni 侧，DELTAV_D 随 Al 成分逐渐减小。这表明除了双空位之外，单空位也有助于扩散。另一方面，在富 Al 侧，DELTAV_D 随 Al 成分急剧减小。这表明扩散主要发生在迁移的激活过程中，因为结构 Ni 空位有助于扩散，然后是扩散。 空位形成的激活过程并不重要。因此，上面已经了解了NiAl中的扩散机制。较少的