DEVELOPMENT OF HIGH PERFORMANCE TiAl ALLOYS USING RAPIDLY SOLIDIFIED POWDER WITH MARTENSITIC STRUCTURE.

使用具有马氏体结构的快速凝固粉末开发高性能 TiAl 合金。

• 批准号: 07555527
• 负责人: NISHIDA Minoru
• 金额: $ 0.45万
• 依托单位: KUMAMOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555527/
• 关键词: TiAl ALLOY; RAPIDLY SOLIDIFIED POWDER; PREP; MICRODUPLEX STRUCTURE; HOT PRESSING; alpha_2 MARTENSITE; SUPERPLASTIC DEFORMATION; GRAIN BOUNDERY SLIDING; マルテンサイト; プラズマ回転電極法; 急冷凝固; 微細等軸粒; ラメラ組織; 相分解

Effect of initial microstructure on the compactibility at elevated temperature in rapidly solidified Ti-rich TiAl alloy powders produced by the plasma rotating electrode process (PREP) has been investigated. There are two kinds of powders with respect to the microstructure. The first one has a surface relief of a martensitic phase and consists of twin related alpha_2 (Ti_3Al) lath platelets, which is referred to as M powder. The second one has a dendritic structure and consists a single phase of alpha_2 with no microstructure other than grain boundary, which is referred to as D powder. alpha_2+gamma (TiAl) microduplex and alpha_2/gamma lamellar structures are formed in M and D powders of the Ti-40 at%Al alloy by heat treatment at 1273 K,respectively. The microduplex structure consist of gamma precipitate in the twin related alpha_2 matrix with the usual orientation relationship. It is difficult to compact the D powder by hot pressing at 1273 K under 50 MPa for 14.4 ks. On the other hand, the M powder is compacted easily by hot pressing with the same condition. The twin related alpha_2 and alpha_2 boundary changes to random ones and the alpha_2 and gamma phases are lost the usual orientation relationship in the duplex structure during the hot pressing. In other words, the low energy boundaries are changed to the high energy ones suitable for grain boundary sliding. Dislocations are scarcely observed inside of both the alpha_2 and gamma crystal grains. It is concluded that the grain boundary sliding is a predominant deformation mode in the M powder during the hot pressing. D and M powders in Ti-45 and 47 at%Al alloys show the same tendency as those in Ti-40 at%Al alloy during hot pressing. From the practical viewpoint the optimization of PREP conditions is also discussed to increase the number fraction of M powder.

研究了等离子旋转电极法（PREP）制备的快速凝固富钛TiAl合金粉末的初始组织对高温压制性的影响。就微观结构而言，存在两种粉末。第一种是由孪晶相关的α_2（Ti_3Al）板条片晶组成的马氏体相的表面浮凸，称为M粉。第二种粉末为树枝状结构，由α_2单相组成，除晶界外没有其他显微组织，称为D粉末。Ti-40at%Al合金的M和D粉末在1273 K热处理后分别形成了α 2 + γ（TiAl）微双相和α 2/γ片层结构。显微双相组织是由γ沉淀物在孪晶相关的α_2基体中以通常的取向关系组成的。在1273 K、50 MPa、14.4ks的热压条件下，D粉末很难实现致密化。另一方面，在相同的条件下，M粉末易于通过热压压制。在热压过程中，与孪晶相关的α_2和α_2晶界变为随机晶界，α_2和γ相失去了通常的取向关系。换句话说，低能量边界被改变为适合于晶界滑动的高能量边界。在α_2和γ晶粒内几乎没有观察到位错。结果表明，在热压过程中，M粉的变形方式以晶界滑动为主。Ti-45和47 at%Al合金中的D和M粉末在热压过程中表现出与Ti-40 at%Al合金相同的趋势。从实用角度出发，探讨了PREP工艺条件的优化，以提高M粉的数量分数。

项目成果

M.Nishida et al: "Effect of Initial Microstructure on the Corpactibility of Rapidly Solidified Ti-rich TiAl Powder" MRS Symposium Proceedings : High-Temperature Ordered Intermetallic Alloys VII.vol.460(in press). (1997)

M.Nishida 等人：“初始微观结构对快速凝固富钛 TiAl 粉末的可塑性的影响”MRS 研讨会论文集：高温有序金属间合金 VII.vol.460（印刷中）。

M.Nishida, A.Chiba, Y.Morizono, T.Kai and J.Sugimoto: "Effect of Initial Microstructure on the Compactibility of Rapidly Solidified Ti-rich TiAl Powder." MRS Symposium Proceedings : High-Temperature Ordered Intermetallic Alloys VII.vol.460 (in press). (19

M.Nishida、A.Chiba、Y.Morizo​​no、T.Kai 和 J.Sugimoto：“初始微观结构对快速凝固富钛 TiAl 粉末压实性的影响”。

M.Nishida et al: "Effect of Initial Microstructure on the Compactibility of Rapidly Soliditied TiAl Powder" MRS Symposium Preceedings : High Temperature Ordered Intermetallic Alloys VII. 460(in press). (1997)

M.Nishida 等人：“初始微观结构对快速凝固 TiAl 粉末致密性的影响”MRS 研讨会序言：高温有序金属间合金 VII。

M.Nishida et al: "Microstructure Dependence of Compactibility of Rapidly Solidified Ti-rich TiAl Powders Produced by Plasma Rotating Electrads Process" Materials Transactions,JIM. 38(in press). (1997)

M.Nishida 等人：“通过等离子体旋转电极工艺生产的快速固化富钛 TiAl 粉末的致密性的微观结构依赖性”Materials Transactions，JIM。

M.Nishida et al: "Grain Refining and Superplastic Compaction of Rapidly Solidified TiAl Powder with Phase Separation of Nonequilibrium α_2 Martensite" Materials Science Forum. vols.233-234. 303-310 (1997)

M.Nishida 等人：“非平衡 α_2 马氏体相分离的快速凝固 TiAl 粉末的晶粒细化和超塑性压实”材料科学论坛，第 233-234 卷（1997 年）。