Cu-12%Al合金线材的马氏体结构及其对力学性能的影响

Martensite structure of Cu-12%Al alloy and its effect on mechanical properties

采用连续定向凝固技术制备Cu-12%Al(质量分数)合金线材,通过改变熔体温度获得不同结构的马氏体,研究马氏体取向和形貌对线材力学性能的影响。结果表明:在引拉速度为10 mm/min、冷却水温为20℃、水流量为400 L/h、熔体温度为1 150或1 200℃的条件下所制备的直径为6 mm的Cu-12%Al线材均为马氏体组织。熔体温度为1 150℃时,定向凝固线材马氏体的母相择优生长面为(100)和(011),马氏体形貌呈枝状和片状,线材的伸长率为5.1%,断口特征为准解理断裂;而熔体温度为1 200℃时,定向凝固线材马氏体的母相择优生长面为(011)、(011)和(011),马氏体形貌全部呈平行片状,线材的伸长率达到16.9%,断口特征为韧性断裂。枝状马氏体在拉伸变形时阻碍位错滑移,抑制马氏体相变的发生;而平行片状马氏体拉伸变形时,有利于不全位错的运动,促进马氏体相变的发生,产生相变塑性,因而具有更强的塑性变形能力。

Cu-12%Al（mass fraction） alloy single crystal wires were prepared by the continuous unidirectional solidification.Various martensite structures were obtained by changing the melt temperature.The effects of martensite orientation and morphologies on the mechanical properties of the alloy wires were investigated.The results show that the Cu-12%Al alloy wires with a diameter of 6 mm have single crystal structure fabricated at drawing velocity of 10 mm/min,cooling water temperature of 20 ℃,water flow rate of 400 L/h,and melt temperature of 1 150 or 1 200 ℃.The preferred growth planes of martensite parent phases are（100） and for the alloy wires fabricated at melt temperature of 1 150 ℃ and martensite morphologies are of the mixture of the forked and lamellar,and their elongations and fracture feature are 5.1% and quasi-cleavage fracture,respectively.The preferred growth planes of martensite parent phases are（011）,and for the alloy wires at melt temperature of 1 200 ℃ and the martensite morphology is lamellar,and their elongations and fracture feature are 16.9% and ductile fracture,respectively.The forked martensite structure can obstruct the dislocation slip and inhibit the occurrence of the martensite transformation.The parallel martensite structure exhibits better plastic deformation capacity induced by martensite transformation because it benefits the movement of the partial dislocation,which results in the occurrence of martensite transformation.