(1. 北京科技大學 材料先進制備技術(shù)教育部重點實驗室，北京 100083；
2. 北京科技大學 新材料技術(shù)研究院，北京 100083)
摘 要: 采用連續(xù)定向凝固技術(shù)制備Cu-12%Al(質(zhì)量分數(shù))合金線材，通過改變?nèi)垠w溫度獲得不同結(jié)構(gòu)的馬氏體，研究馬氏體取向和形貌對線材力學性能的影響。結(jié)果表明：在引拉速度為10 mm/min、冷卻水溫為20 ℃、水流量為400 L/h、熔體溫度為1 150或1 200 ℃的條件下所制備的直徑為6 mm的Cu-12%Al線材均為馬氏體組織。熔體溫度為1 150 ℃時，定向凝固線材馬氏體的母相擇優(yōu)生長面為(100)和 ，馬氏體形貌呈枝狀和片狀，線材的伸長率為5.1%，斷口特征為準解理斷裂；而熔體溫度為1 200 ℃時，定向凝固線材馬氏體的母相擇優(yōu)生長面為(011)、 和 ，馬氏體形貌全部呈平行片狀，線材的伸長率達到16.9%，斷口特征為韌性斷裂。枝狀馬氏體在拉伸變形時阻礙位錯滑移，抑制馬氏體相變的發(fā)生；而平行片狀馬氏體拉伸變形時，有利于不全位錯的運動，促進馬氏體相變的發(fā)生，產(chǎn)生相變塑性，因而具有更強的塑性變形能力。
關(guān)鍵字: Cu-12%Al合金；連續(xù)定向凝固；馬氏體；相變塑性
its effect on mechanical properties
（1. Key Laboratory for Advanced Materials Processing, Ministry of Education,
University of Science and Technology Beijing, Beijing 100083, China;
2. Institute for Advanced Materials and Technology,
University of Science and Technology Beijing, Beijing 100083, China）
Abstract: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.
Key words: Cu-12%Al alloy; continuous unidirectional solidification; martensite; phase transformation plasticity
