1992 Fiscal Year Final Research Report Summary
Strengthening Mechanism and Alloy Design for a Heat-Resisting Light Intermetallics Titanium Aluminide
| Project/Area Number |
03650564
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
金属材料(含表面処理・腐食防食)
|
|---|
| Research Institution | TOHOKU UNIVERSITY |
|---|
Principal Investigator |
MARUYAMA Kouichi Tohoku University,Faculty of Engineering,Associate Professor, 工学部, 助教授 (90108465)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
OIKAWA Hiroshi Tohoku University,Faculty of Engineering,Professor, 工学部, 教授 (30005243)
|
|---|
| Project Period (FY) |
1991 – 1992
|
| Keywords | Titanium aluminide / Intermetallics / Heat-Resisting Materials / Creep Deformation / Deformation Mechanism / Dynamic Recrystallization / Constitutive Creep Equation / Alloy Design |
|---|
| Research Abstract |
Titanium aluminide is one of candidates for heat resisting materials because of its low specific gravity and high elevated temperature strength. This study aims at elucidating strengthening mechanism of the titanium aluminide and developing an alloy design system for heat resisting materials. The results are summarized as follows:
1. High temperature deformation of titanium aluminide : gamma-TiAl shows three different creep deformation mechanisms depending on stress level. At high stress regime creep is controlled by dynamic recrystallization,whereas dislocation motion itself controls creep at low stresses. Relative strength of alpha-Ti solid solution alloy,alpha_2-Ti_3Al and gamma-TiAl was determined as functions of temperature and strain rate.
2. Development of theta concept : In order to analyze complicated creep behavior at high temperature and to evaluate long term creep properties,we need constitutive creep equation. A creep equation for non-steady state creep,i.e.theta concept was proposed in this study. By using this concept,we could understand the complicated behavior in a simple manner and predict long term creep properties with high accuracy. Physical basis of the creep equation was also discussed in this study.
3. A concept of alloy design for heat resisting materials : Three material constants are obtained from creep curve analysis by means of the theta concept. In order to develop alloy design system,the following problems have to be solved: How to correlate the material constants to high temperature creep properties,and how to control the material constants by means of metallurgical treatments. The material constants of the theta concept are related to the creep properties by simple equations. It was shown how metallurgical factors effect the materials constants,suggesting a concept of the alloy design.
|
