Phase Separation Morphology Evolution And Properties Characterization Of Cu₃₅Fe₆₅ Alloy Prepared By Laser Melting Deposition

Cu-Fe alloy has attracted wide attention due to its low cost and excellent comprehensive performance.It has been widely used in aerospace,mechanical electronics,metallurgy and other fields.Cu-Fe has a positive mixing enthalpy and is a typical phase separation alloy.When the melt is supercooled to its metastable and immiscible region,phase separation can easily occur.The microstructure and morphology of the phase-separated alloys can directly affect their properties.In the phase-separated alloys prepared by traditional techniques,the structure tends to segregation or even delaminating under the factors of gravity,cooling rate and so on.It will seriously affect the performance of the phase-separated alloys.Compared with the traditional technology,laser melting deposition（LMD）technology has the advantage of simple process,near-net-forming,short processing cycles and low cost.Besides that,the molten pool in LMD is smaller,resulting in a faster cooling and solidification rate,and usually making the melt in a supercooled state.Therefore,the preparation of Cu-Fe alloy by LMD technology may reduce the segregation to a certain extent,obtain uniform immiscible alloy,and improve the alloys quality.However,the properties of the alloy prepared by LMD technology usually can only be controlled by changing the grain size and shape.The research on the preparation and microstructure evolution of the Cu-Fe alloy by LMD may further tune the microstructure at the phase scale,and improve the properties and expand its application fields.In the present paper,Cu₃₅Fe₆₅ alloy was prepared by LMD technology with high-purity spherical mixed powder as raw material.The influence of laser output power and scanning speeds on the microstructure of Cu₃₅Fe₆₅ alloy and the separation mechanism were studied systematically.The Cu-Fe samples prepared by LMD are all present typical phase separation morphology.It was found that Cu-Fe alloy were mainly composed ofα-Fe phase and Cu phase.In the alloy,the secondary phase separation phenomenon can be obviously observed.The primary phase separation forms Cu-Fe dendrites arranged in the Cu-rich matrix along the printing direction.The secondary phase separation occurs within the Cu-Fe dendrites,which forms Cu and Fe nanostructure.The feature size of the primary separation decreases with the increasing scanning speeds and the decreasing laser output power.In addition,the mechanical properties,magnetic properties and electrical conductivity of the LMD Cu₃₅Fe₆₅ alloy were studied.After chemical etching,oriented hierarchical porous structure was prepared from the Cu₃₅Fe₆₅ alloy.The morphology evolution and the wettability of the oriented hierarchical porous structure were systematically studied.The contact angle between the water and the etching Cu-Fe alloy firstly increases rapidly and then tends to be stable.The presented work provides an important insight into the structure evolution as well as potential applications of the LMD prepared Cu-Fe alloy with phase separation structure.