(華南理工大學(xué) 材料科學(xué)與工程學(xué)院，廣州 510640)
摘 要: 研究了不同孔隙特征多孔NiTi合金的內(nèi)耗與相變行為及其頻率響應(yīng)，提出用等效內(nèi)耗參數(shù)表征多孔NiTi合金實(shí)體部分的阻尼能力。結(jié)果表明：多孔NiTi合金內(nèi)耗峰產(chǎn)生的主要誘發(fā)因素是相變及應(yīng)力誘發(fā)下各種界面(含孿晶界、相界面等)的遷移；在不同的加載頻率下，多孔NiTi合金的內(nèi)耗值曲線按雙曲線規(guī)律變化；在相同的頻率和振幅下，孔隙率、孔隙尺寸和開孔度的增加導(dǎo)致與界面遷移相關(guān)內(nèi)耗幅值有所削弱；各內(nèi)耗峰值溫度也受到孔隙參數(shù)的影響；多孔NiTi合金的等效內(nèi)耗峰值明顯高于致密NiTi合金。
關(guān)鍵字: 多孔NiTi合金；內(nèi)耗；相變；孔隙率；頻率效應(yīng)
porous NiTi alloys with variable porosities
（School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China）
Abstract:The damping behaviours of porous NiTi alloys with different pore characteristics were studied, and a new parameter for porous NiTi alloys, i.e., equivalent internal friction, was proposed to characterize their effectiveness in energy absorption. The results show that the internal friction peaks of porous NiTi alloys are induced by phase transformation and the stress induces hysteretic motions of interfaces such as twin boundaries and phase boundaries. At different frequencies, the intensity of internal friction peaks changes following the hyperbolic relation. Under the same testing conditions (i.e., at certain frequency and amplitude), the increases of porosity, pore-size and open porosity of the alloys lead to the decrease of amplitude of the internal friction associated with interface movement. The increase in porosity can also result in change of internal friction peak temperatures. The porous NiTi alloys have obviously high equivalent internal friction value than the dense NiTi alloys.
Key words: porous NiTi alloy; internal friction; phase transformation; porosity; frequency effect
