新型Cu-Fe-C复相合金的制备及其变形行为

Development and Deformation Behavior of Advanced Cu-Fe-C Alloy with Dual-Phase Microstructure

采用真空熔炼和快速凝固方法制备了组织优异的新型Cu-Fe-C复相合金,并通过金相、SEM、TEM、XRD以及力学性能测量分别对复相合金铸态和冷轧态显微组织变化和变形行为进行了研究。结果表明,当凝固界面推移速率满足Vc<V<Vp时,微米级和纳米级的Fe-C相可均匀弥散分布于合金基体内,不过微米级Fe-C粒子对应的此速率范围远小于纳米级Fe-C粒子的;由于溶质元素Fe在Cu基体内的固溶和不同尺寸Fe-C相的存在,使得熔铸态复相合金具有较高的加工硬化率(n=0.3628);80%冷轧变形可诱发合金基体内的Fe-C相发生γ-Fe→α-Fe相变,充分利用这一相变可用于调控Cu-Fe-C复相合金的强度和加工变形性能;虽然熔铸态和冷轧态合金均具有较好的协调变形性能,但是相比而言,Fe-C相处于FCC结构时的熔铸态合金可表现出更好的协调变形行为;此外,本文根据复相铜合金的组织演化以及拉伸断口形貌提出了该类合金协调变形和断裂模型示意图。

An advanced Cu-Fe-C alloy with dual-phase structure was prepared by combining vacuum melting and rapid solidification. The microstructure evolution and deformation behavior of the alloy in the as-cast and rolled states were studied by OM,SEM,TEM and XRD characterization,and mechanical property measurements. The results show that when the moving speed of freezing interface satisfies the relationship of VcVVp,both micro-scale and nano-scale Fe-C particles are uniformly distributed in the alloy matrix,but the range between Vc and Vp for micro-scale particles is much narrower than that of nano-scale particles. Due to the solution of Fe in the Cu matrix and the existence of Fe-C particles with different sizes,the Cu-Fe-C alloy in the as-cast state possesses a much higher work hardening exponent（n=0.3628）. The phase transformation of Fe-C particles from γ-Fe to α-Fe can be induced by cold rolling 80%,which can be greatly used to control and optimize the strength and deformation performance of Cu-Fe-C alloy. Although the deformability of Cu-Fe-C alloy in both the as-cast and rolled states is good,compared with the cold rolled state,the alloy in the as-cast state possesses a much better coordinative deformation performance owing to the fcc structure of Fe-C phases in this state. Additionally,according to the microstructure evolution and tensile fracture morphologies of Cu-Fe-C alloy with a dual-phase structure,the coordinative deformation and fracture models were put forward.