热型连铸CuAlNi形状记忆合金丝的性能研究

Mechanical and Memory Performance of CuAlNi Shape Memory Alloy Wires Cast by Ohno Continuous Casting Process

用热型连铸法制取1.5mm的柱晶CuAlNi合金丝,具有轴向排列的柱晶组织。经过900℃固溶处理,拉伸曲线与单晶的相似,具有两个阶段的马氏体转变,抗拉强度可达633MPa,延伸率14.95%。在4%的固定应变下,反复拉伸疲劳断裂次数高达38560次,形状回复率为100%。反复拉伸后在晶界上形成一种新相,有效地松弛了晶界上的应力集中,可能是疲劳寿命大幅度提高的原因。

CuAlNi alloy wires in 1.5 mm diameter were cast by ohno continuous casting process to obtain a longitudinal columnar structure. After solution treatment at 900°C, the stress curve of the wires shows two martensitic transformation stages which is similar to that of single crystal structure. The wires show an ultimate tensile strength of 633 MPa, elongation of 14.95%. Under 4% strain, the number of repeat tensile fatigue rupture is 38560 cycles and the recovery rate keeps up 100%. After repeat tensile, a new phase forms along the boundaries so as to release stress concentration. This is probably the cause of great enhancement of repeat tensile fatigue life.