報告書番号

T98046

タイトル（和文）

Ti-Ni-Cu形状記憶合金の繰返し変形特性に及ぼすCu添加量の影響

タイトル（英文）

Effect of Cu Content on Cyclic Behaviors in Ti-Ni-Cu Shape Memory Alloy

概要 （図表や脚注は「報告書全文」に掲載しております）

Ti-Ni形状記憶合金は，アクチュエ－タやセンサ－など多くの機器で実用化されているが，形状記憶効果や超弾性の性質を繰返し条件下で使用するため，機能や寿命の劣化が大きな問題となっている．特性改善の方法として，Ti-Ni合金に第３元素を添加することが注目されている．本報では，Ti-Ni-Cu合金を溶解法により作製し，機能特性の改善効果に及ぼすCu添加量の影響について評価した．熱・力学的および超弾性サイクル条件下で繰返し特性変化について調べ，Cu添加量の機能特性に及ぼす影響を考察した．その結果，変態温度ヒステリシスはCuを添加することにより減少し，回復応力はCu濃度の増加とともに増大する．また，非回復ひずみはCu濃度の増加とともに減少し，さらに有効ひずみエネルギ－は変形ひずみ範囲によって異なり，変形ひずみは3%以下ではCu濃度の影響が認められるが，3%を超えるとCu濃度の依存性は認められない．

概要 （英文）

Ti-Ni shape memory alloy has benn used for many applications such as actuators, sensors, and so on. However, since the shape memory and superelastic functions are often used under cyclic conditions, degradation of these functions and fatigue life have been important concerns. In order to improve functions and to increase fatigue life, addition of Cu as a third element is attractive option, because temperature/stress hysteresis decrease, and recovery stress and strain energy increase with increasing in Cu content. In this paper, Ti-Ni-Cu alloy ingots were made using a high frequency induction vacuum furnace, the effect of Cu content on functional characteristics is investigated. Experiments were carried out under thermo-mechanical and superelastic cyclic conditions. The thermo-mechanical cyclic tests are carried out by repeating the combination of the thermal cycle and the loading-unloading cycle under constant heating and cooling temperature, and the superelastic cyclic tests are carried out by repeating loading-unloading under the constant heating temperature higher than austenite finish temperature. The results show that the transformation temperature hysteresis decrease with Cu content, and the recovery stress increases with the increse in Cu content. It is also noted that the irrecoverable strain decreases with the increase in Cu content. Furthermore, the available strain energy increases with increasing Cu content. But, the Cu content has little effect on available strain energy in the deformation strain range of beyond 3%.

報告者

キーワード