Microstrucrure of Multi-phase Ti_5Si_3 Base Intermetallic Compounds Fabricated by Adding Ternary Element and Improvement of Their Ductility

添加三元元素制备多相Ti_5Si_3基金属间化合物的显微结构及其延展性的提高

• 批准号: 08650832
• 负责人: ISONISHI Kazuo
• 金额: $ 1.34万
• 依托单位: Shiga Univ.
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650832/
• 关键词: Ti Silicide; intermetallic compound; ternary element; alpha-Ti; beta-Ti; mechanical properties; fracture toughness; Ti_5Si_3; α-Ti; β-Ti; Ti-シリサイド; アーク溶解; V添加

Ti_5Si_3 exhibits low density, high melting temperature and adequate oxidation resistance. However, the compound is very brittle due to the complex crystal structure, D88. Hence, many cracks are introduced during ingot metallurgical fabrication process by anisotropic thermal expansion coefficient. Therefore, I tried to form ductile second phase, beta-Ti, by adding ternary element, and make clear the effect of that on mechanical properties. It is impossible that Ti-Si system realizes (Ti_5Si_3+beta-Ti) dual phase alloy. V and Mo were chosen as additives, as those were strong beta former of Ti alloy. The addition of 10mol%V (Ti-3Omol%Si-lOmol%V) or 5mol%Mo (Ti-32mo1%Si-5mol%Mo) was able to stabilize beta-Ti at room temperature after stabilization treatment at 1473K for 86.4ks. Chemical compositions of each phase in the samples were obtained by EDS analysis. Using the results of quantitative observations and X-ray diffraction to identify the phases. Ti-Si-V and Ti-Si-Mo isothermal section at the area around (Ti_5Si_3+Ti) dual phase composition at room temperature were able to illustrated. D88 phase can dissolve over 20mol%V and 14vol%Mo in Ibis investigation. D88 phase in the Ti-37.Smol%Si-20mol%V alloy showed enhanced fracture toughness of 185MPa・m^<1/2> compared to the value of 1.17 of stoichiometric D88 phase (Ti-37.5mol%Si). Mo addition had an effect of microstructure refinement that was decreasing aspect ratio of primary Ti_5Si_3 grain and spheroidizing of eutectic structure (especially Ti_5Si_3 phase). This microstructural effect had prevented to introduce cracks during cooling after melting.

Ti_5Si_3具有低密度、高熔点和良好的抗氧化性能。然而，由于复杂的晶体结构D88，该化合物非常脆。因此，在铸锭冶金制造过程中，由于热膨胀系数的各向异性，导致许多裂纹的产生。因此，本文尝试通过添加三元元素来形成韧性第二相β-Ti，并研究其对力学性能的影响。Ti-Si系不可能实现（Ti_5Si_3+ β-Ti）双相合金化。选择V和Mo作为添加剂，因为它们是钛合金的强β形成剂。10mol%V（Ti-30mol%Si-10mol%V）或5mol%Mo（Ti-32mol%Si-5mol%Mo）的加入可使β-Ti在1473 K稳定化处理86.4ks后在室温下稳定化。通过EDS分析得到了样品中各相的化学组成。利用定量观察和X射线衍射的结果来鉴定物相。在（Ti_5Si_3+Ti）双相组成附近的Ti-Si-V和Ti-Si-Mo等温截面上，可以显示出室温下的等温截面。在Ibis研究中，D88相的溶解量超过20mol%V和14vol%Mo。Ti-37.5mol%Si-20mol%V合金中D88相的断裂韧性为185 MPa·m^<1/2>，比化学计量比D88相（Ti-37.5mol%Si）的断裂韧性1.17有所提高。Mo的加入细化了Ti_5Si_3初生晶粒的长径比，使共晶组织（尤其是Ti_5Si_3相）球化。这种微观结构效应防止了在熔化后冷却期间引入裂纹。

项目成果

K.Isonichi: "Characteristics of Four Ti_5Si_3 - Base Allay Compacts Fabricated by Mechanical Alloying and Vacuam Hot Pressing" Proceedings of the 1998 Powder Metallurgy World Congress. 5. 501-506 (1998)

K.Isonichi：“通过机械合金化和真空热压制造的四种 Ti_5Si_3 基合金复合体的特性”1998 年粉末冶金世界大会论文集。

K.Isonishi: "Formation of Ductile α/β-Ti Phase in Ti_5Si_3 Intermetallic Compound and Their Effects on Microstructure and Mechanical Properties" Proc.8th International Conference of Mechanical Behavior of Metals. in press. (1999)

K. Isonishi：“Ti_5Si_3 金属间化合物中延展性 α/β-Ti 相的形成及其对微观结构和机械性能的影响”Proc.8th 国际金属机械行为会议（1999 年）。

K.Isonishi: "Formation of Ductile alpha/beta-Ti phase in Ti_5Si_3 Intermetallic Compound and Their Effects on Microstructure and Mechanical Properties" Proc.8th International Conference of Mechanical Behavior of Metals. in press.

K.Isonishi：“Ti_5Si_3 金属间化合物中延性 α/β-Ti 相的形成及其对微观结构和机械性能的影响”Proc.8th 国际金属机械行为会议。

K.Isonishi: "Characteristics of Four Ti_5Si_3-Base Alloy Compacts Fabricated by Mechanical Alloying and Vacuam Hot Pressing" Proc.1998 Powder Metallurgy World congress. 5. 501-506 (1998)

K.Isonishi：“通过机械合金化和真空热压制造的四种Ti_5Si_3基合金坯体的特性”Proc.1998粉末冶金世界大会。

K.Isonishi: "Charateristics of Four Ti_5Si_3-base Alloy Compacts Fabvicated by Mechanical Alloying and Vacuum Hot Pressing" Proc.1998 Powder Metallurgy World Congress. 5. 501-506 (1998)

K.Isonishi：“通过机械合金化和真空热压制造的四种 Ti_5Si_3 基合金坯体的特性”Proc.1998 粉末冶金世界大会。