论文标题
在polycrystalline ni $ _ {50.4} $ ti $ _ {49.6} $的超弹性拉伸循环中抑制声发射
Suppression of acoustic emission during superelastic tensile cycling of polycrystalline Ni$_{50.4}$Ti$_{49.6}$
论文作者
论文摘要
我们研究了在马氏体过渡期间出现的声发射（AE），在原型超弹性/弹性/弹性合金ni $ _ {50.4} $ ti $ _ {49.6} $（at。％）驱动的典型超弹性/弹性/弹性合金ni $ _ {50.4} $ _ {50.4} $ _ {50.4} $ _ {50.4} $ _ {50.4} $ _ {50.4} $ _ {50.4} $）中。我们使用两个独立的AE传感器来定位AE事件，并专注于从机械测试机的握把上产生的AE的贡献。在第一次机械载荷期间，存在明显的AE活性，这主要是由于成核和宽阔的lüders样带在向前的马氏体转变期间（使用可见光的光和红外（IR）辐射成像，从而导致晶间相互作用的持续变化。在随后的卸载后反向马氏体过渡和连续的加载/卸载周期中，AE活性被抑制，为此，lüders样带狭窄且修改了晶间相互作用的程度较小。第一次加载后，我们发现与马氏体转变相关的AE活性很弱，我们建议这是因为Ni-Ti中的弹性各向异性和应变不相容性很低。我们还发现，由于保留的马氏体增加，AE活性在机械循环方面变得较弱。
We investigate acoustic emission (AE) that arises during the martensitic transition in a polycrystalline specimen of the prototypical superelastic/elastocaloric alloy Ni$_{50.4}$Ti$_{49.6}$ (at. %) driven using tensile strain. We use two independent AE sensors in order to locate AE events, and focus on contributions to the AE that arise away from the grips of the mechanical testing machine. Significant AE activity is present during the first mechanical loading primarily due to nucleation and growth of wide Lüders-like bands during the forward martensitic transition (imaged using visible light and infrared (IR) radiation) that lead to persistent changes in intergranular interactions. AE activity is suppressed during the subsequent reverse martensitic transition on unloading, and in successive loading/unloading cycles, for which the Lüders-like bands narrow and modify intergranular interactions to much less extent. After the first loading, we find that the AE activity associated with the martensitic transition is weak, and we suggest that this is because the elastic anisotropy and strain incompatibility in Ni-Ti are low. We also find that the AE activity becomes weaker on mechanically cycling due to increased retained martensite.
