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以4种速度连铸了柱状晶组织的CUALNI记忆合金丝并热处理,检验其晶粒长大及弯曲疲劳性能。连铸速度大于240MM/MIN,Γ2相的析出被抑制;速度达480MM/MIN时由于凝固前沿液相受到激冷而形成等轴晶。360MM/MIN为柱状晶加热长大的临界连铸速度。超过此速度,加热时晶粒将急剧长大。临界连铸速度以下提高连铸速度可细化晶粒,经热处理消除内应力后,弯曲疲劳断裂次数可大幅提高。
CuALNI memory alloy wires with columnar grain structure were continuously cast at 4 different speeds and heat treated to test their grain growth and bending fatigue properties. Casting speed is greater than 240MM / MIN, Γ2 phase precipitation is inhibited; speed 480MM / MIN due to the solidification of the front of the liquid-phase is chilled to form equiaxed. 360MM / MIN for the columnar crystal growth of the critical rate of continuous casting. Beyond this speed, the grains will grow sharply when heated. The critical continuous casting speed to improve the continuous casting speed can be refined grain, heat treatment to eliminate stress, bending fatigue fracture frequency can be significantly increased.