超细片层NbTi/TiNi记忆合金复合材料的 制备与功能特性

Preparation and functional properties of ultrafine lamellar NbTi/TiNi shape memory alloy composites

关键词:  记忆合金复合材料  制备  马氏体相变  负膨胀  应变软模  共晶转变  特性

Key words:  shape memory alloy composites  preparation  martensitic transformation  negative thennal expansion strain induced modulus softening  eutectic transformation  property

摘要:

基于NbTi-TiNi共晶铟相变，经成分分析,通过电弧熔炼制备几种具有NbTi和TiNi记忆合金铸态双相组织的 NbTiNi合金。这种合金是一种原位自生的NbTi/TiNi记忆合金复合材料，具有复合比可控(通过调整Ni或Nb含 量)、可逆马氏体相变溫度可调(通过调整Ti/Ni比例)的特点。通过对其辅以常规的锻造、拔丝等大变形T艺加工， 使MbT彳和TiNi组元细化至微米级别，进一步得到复合组元比表面大、分布均匀、界面强度高的超细片层MbTi/TiNi 记忆合金复合丝材料。通过热膨胀仪和万能拉伸试验机对其进行热膨胀和力学性能测试。结果表明，该复合材料 不似具有很高的屈服强度(超过L6 GPa),还具有负膨胀点记忆效应、应变软模效应等新功能特性。

Abstract:

Based on the eutectic transformation of NbTi-TiNi, a series of hypereutectic NbTiNi alloys with NbTi and TiNi shape memory alloy dual phase structure were designed and obtained by arc mellir^ method. Such alloy is a kind of in-situ NbTi/TiNi shape memory alloy composile with NhTi matrix and TiNi functional component. Tlie reversible martensitic transformation temperature and the volume fraction of the embedded TiNi can be controlled by adjusting the Ti/Ni atomic ratio and Ni (Nb) content of the alloy. After forging and wire drawing the NbTiNi alloy ingots, NbTi and NiTi phases became micron scale lamellas. Then an ultrafine lamellar NbTi/TiNi shape memory alloy composite wire with high yield strength was obtained. As the specific surface area of ultrafine TiNi lamellar is Urge，and the interface bonding of the NbTi/TiNi phase is much strong, the coupling effect between the NiTi lamellar and NbTi matrix can be represented effectively. The thermal expansion and mechanical properties were tested using dilatometer and universal tensile test machine. The results show that some new functional properties were observed, such as high yield strength (more than 1.6 GPa)，negative thermal expansion point memory effect and strain induced modulus softening effect.