应力制约双程形状记忆材料的相交特性

TRANSFORMATION OF TWO WAY SHAPE MEMORY MATERIAL CONSTRAINED BY STRESS

利用应力对双程形状记忆(TWSM)材料相变的制约作用,在NiTi合金TWSM材料中实现速动相变和速动TWSM效应。研究了应力场的形式、大小对热滞回线的影响;计算了相变驱动力ΔG_c随温度变化的关系并给出速动相变的热力学解释。

The snap-acting transition and snap-acting two way shape memory(TWSM) effect have been obtained in a TWSM spring made of Ni51Ti49 alloyusing the constrained effect of stress on the driving force of TWSM element. Whenthe snap-acting transition has been realized, M_s=M_f and A_s=A_f; hysteresis is rec-tangular, the height (TWSM effect) and width (hysteresis) of the rectangle can bereadjusted by means of constrained stress. The results of resistance measurementsshow that the snap acting TWSM effect mentioned above was supplied mainlyfrom the transformation of P-R. The gradients of the driving force with respectto temperature near critical point have been calculated. The thermodynamic modelhas been proposed to account for the snap-acting transformation.