| Project/Area Number |
60460190
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Physical properties of metals
|
|---|
| Research Institution | TOHOKU UNIVERSITY |
|---|
Principal Investigator |
HONMA Toshio Tohoku University, 選鉱製錬研究所, 教授 (60006020)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
SHUGO Yoshiro Tohoku University, 選鉱製錬研究所, 助手 (40006052)
MATSUMOTO Minoru Tohoku University, 選鉱製錬研究所, 講師 (30006043)
|
|---|
| Project Period (FY) |
1985 – 1986
|
| Project Status |
Completed (Fiscal Year 1986)
|
| Budget Amount *help |
¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 1986: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1985: ¥4,500,000 (Direct Cost: ¥4,500,000)
|
|---|
| Keywords | Thermoelastic Martensitic Transformation / Shape Memory Effect / Precipitation / TiNi Alloy / Aging Treatment / Habit Plane / Shape Memory Alloy / 全方位形状記憶効果 |
|---|
| Research Abstract |
Ni rich TiNi alloys (Ti-51-52at%Ni) exhibit the all-Round Shape Memory Effect by aging under constrain. The aim of this research project is to clarify the mechanism of this All-Round Shape Memory Effect. Shape memory effects of Ti-51 and 52at%Ni specimens were investigasted under the various conditions of constrained aging by means of optical microscope and eleotron microscope. The results are as follows.
1. The TTT diagrams of precipitates in this alloy were made between 300-600゜C. Precipitates were <Ti_3> <Ni_4> (precisely <Ti_11> <Ni_14> ), <Ti_2> <Ni_3> and Ti <Ni_3> . Ti <Ni_3> is stable and the others are metastable phases.
2. Fine and dispersed precipitates of <Ti_3> <Ni_4> with coherent grain boundary cause the All-Round Shape Memory Effect. This effect does not appear in the case of bigger precipitates grown up.
3. The crystal structure of <Ti_3> <Ni_4> is rhombohedral structure (a=6.72 <。!A> , <alpha> =113.9) with ordered atomic arrangement.
4. The lenticular precipitate <Ti_3> <Ni_4> has the anisotropy in both of inner (compression stress) side and outer (tension stress) side.
5. Against the stress axis, the semimajor axis of presipitate <Ti_3> <Ni_4> is perpendecular in the compression side and parallel in the tension side, respectively.
6. The growth direction of intermediate (R) phase and martensite (M) phase which generate in specimen during cooling is the best convenient direction which accomodates the internal strain between parent phase and precipitates, especially the strain in the direction of semiminor axis of precipitate. Therefore, after the growth of R phase with single variant around precipitate, martensite phase appears. As the result ofthe difference of lattice constant the compression stress side elongates and the tension stress side shrinks in bending constrained specimen during cooling. It is concluded that the shape of the specimen changes spontaneously and the All-Round Shape Memory Effect appears during cooling.
|
