In order to improve the linear recovery behavior, TiNi shape memory alloy springs were samariumed at 550°C for 4 hours with SmH3 as samarium source, in a vacuum furnace. The phase of samariumed layer was determined by X-ray diffractometer (XRD). The fracture surface of TiNi SMA spring was investigated by scanning electronic microscope (SEM). The experimental results indicate that a thick samariumed layer composed of NiSm intermetallics existed on the fracture surface. Additionally, a new idea of linear recovery behavior in shape memory alloy (SMA) has been proposed, and its properties have been defined. The reversion measurements show that the linear recovery properties of TiNi SMA were obviously improved. The temperature range of the linear reversion (Tw) was enlarged from 4°C to 8’C, The ratio of linear reversion was increased from 54% to 75%, the proportion of linear reversion (PL) was increased from 56% to 70%, and the proportion of non-linear reversion (Ps) was decreased from 44% to 10%, but the proportion of total reversion (PT) has a little decrease. These results were attributed to the strengthening effect of NiSm intermetallics.
展开▼
