摘要
采用泰勒法制备了直径范围在30~100μm之间的玻璃包裹Ni-Mn-In-Co合金纤维。利用综合物性测量系统(PPMS)研究了磁场对制备态和退火态纤维马氏体相变温度的影响,并且从M-B曲线中分别计算得出了制备态和退火态纤维的磁热效应。研究结果表明:制备态纤维在室温下为7M马氏体结构。在制备态和退火态纤维中,奥氏体相变开始温度随外加磁场变化速率(ΔAs/ΔB)分别为-1.6和-4 K/T。退火态纤维在As点附近发生磁场诱发马氏体向奥氏体逆相变。退火态纤维最大磁熵变为3.0 J/(kg·K),远大于制备态纤维的0.5 J/(kg·K)。Ni-Mn-In-Co合金纤维的大磁熵变和低成本使其成为最具潜力的磁制冷材料之一。
Ni-Mn-In-Co microwires with diameter of 30-100 μm are prepared by glass-coated metal filaments(Taylor–Ulitovsky) method. The effects of magnetic field on martensite transformation temperature in the as-prepared and annealed microwires are investigated using a physical property measurement system(PPMS). Magnetocaloric effect(MCE) attributed to field-induced austenite transformation in the as-prepared and annealed microwires is analyzed indirectly from the isothermal magnetization(M-B) curves. The as-prepared microwire has a 7-layer modulated martensite structure(7M) at room temperature. The changes of austenite starting temperature induced by an external magnetic field(ΔAs/ΔB) in the as-prepared and annealed microwires are-1.6 and-4 K/T, respectively. Inverse martensite to austenite transformation exists in annealed microwires when an external magnetic field is applied at temperatures near As. The entropy change(ΔS) obtained in the annealed microwires is 3.0 J/(kg·K), which is much larger than that in the as-prepared microwires 0.5 J/(kg·K). The large entropy change and low price make Ni-Mn-In-Co microwires a potential working material in magnetic refrigeration.
基金
Project(51001038)supported by the National Natural Science Foundation of China
关键词
铁磁形状记忆合金
纤维
马氏体相变
磁热效应
磁化曲线
magnetic shape memory alloys
microwires
martensitic transformation
magnetocaloric effect
magnetization curve