微量硼添加对 CuNiMnFe 合金组织与性能的影响

摘要

为了改善 CuNiMnFe 多元合金组织内树枝晶尺寸及成分偏析，提高合金力学性能，在合金熔炼过程中添加微量硼进行变质处理，采用扫描电子显微镜、透射电子显微镜及能谱分析仪对 CuNiMnFe 合金的组织形貌及物相进行表征，并采用布氏硬度计和万能材料试验机分别对合金硬度和抗拉强度进行测试。结果表明：硼元素对CuNiMnFe 合金组织变质效果明显，在0~0.15%B(质量分数)范围内，随着硼添加量的增加，CuNiMnFe 合金组织中树枝晶得到细化，二次晶臂间距减小，共晶β相减少，枝晶内析出颗粒状次生β相与钉状γ相增多。当硼的添加量为0.10%时，合金组织内树枝晶二次晶臂间距最小，板条状共晶β相基本消失，枝晶内颗粒次生β相与钉状γ相明显。CuNiMnFe 合金铸态硬度及热处理后的硬度也随着硼的添加量的增加呈先增大后减小的趋势。当硼的添加量为0.10%时，合金铸态硬度达到峰值，热处理后硬度仍保持最大值 HB380，同时，合金抗拉强度达到1130 MPa。%In order to refine the dendrite and eliminate the segregation of CuNiMnFe alloy, the molten CuNiMnFe alloy was modified by trace boron addition. The effect of the modification treatment on microstructures and properties of the CuNiMnFe alloy was studied, the microstructure and phase were characterized by the scanning electron microscope, transmission electron microscope and energy dispersive spectrum, and the hardness and tensile strength of alloys were measured on Brinell hardness tester and universal material testing machine, respectively. The results show that B addition has a significant effect on the microstructures of CuNiMnFe alloy. In the range of 0−0.15%B (mass fraction), the increased boron addition can refine the dendrite microstructure, reduce the secondary dendrite arm spacing (SDAS) and the amount of eutectic β phase, while the precipitation of the secondary β and nail­head γ phase inside the dendrites increase. At 0.10%B, SDAS is the least, the lamellar eutectic β phase almost disappears, and the obvious secondary βphase and nail­head γ phase inside the dendrite. With the boron adding, the as­cast hardness and aged hardness of the CuNiMnFe alloy increase at first, and then decrease. The as­cast CuNiMnFe alloy with 0.1%B addition has the peak hardness, and the aged peak hardness can remain the maximum hardness value of HB380. The tensile strength of aged CuNiMnFe alloy can reach up 1 130 MPa.