(1. 蘇州熱工研究院有限公司 表面工程研究所，蘇州 215004；
2. INM-Leibniz Institute for New Materials, Saarbrucken 66123, Germany)
摘 要: 利用維氏四棱錐壓痕方法，通過溫度控制在NiTi合金中獲得凸起-平整的雙程形狀記憶效應(yīng)表面。通過研磨剝層法，發(fā)現(xiàn)隨著消除深度的增加所獲得的凸起高度和直徑減小，在消除160 μm深度后，表面凸起現(xiàn)象消失，并從理論上定量分析該深度所對應(yīng)的臨界應(yīng)變大小。實驗表明：雙程形狀記憶效應(yīng)是通過對形狀記憶合金進(jìn)行溫度-應(yīng)變循環(huán)變形而獲得。因此，可能存在一定的臨界應(yīng)變，在低于該應(yīng)變時，材料不能表現(xiàn)雙程形狀記憶效應(yīng)。
關(guān)鍵字: NiTi合金；雙程形狀記憶效應(yīng)；臨界應(yīng)變；應(yīng)變分布；壓痕
（1. Division for Surface Engineering, Suzhou Nuclear Power Research Institute Co., Ltd., Suzhou 215004, China;
2. INM-Leibniz Institute for New Materials, Saarbrucken 66123, Germany）
Abstract:Two-way shape memory effect (TWSME) surface in NiTi was obtained using Vickers four-sided pyramidal indentation method, namely, the switchable surface between protrusions and flat state controlled by temperature. By gradual grinding off the deformed layer after indenting, the diameter and height of the protrusions decrease as increasing the removal layer. It is found that no protrusions are observed after 160 μm thick layer was removed. The critical microstrain at this depth is further theoretically calculated. It shows that TWSME can be obtained by means of thermomechanical training in shape memory alloys. Thus, there probably exists a critical microstrain, below which no TWSME will occur.
Key words: NiTi alloy; two-way shape memory effect; critical strain; strain distribution; indentation
