Mechanical Properties and Microstructural Characterization of Cu-4.3 Pct Sn Fabricated by Selective Laser Melting
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SELECTIVE laser melting (SLM) is an additive manufacturing technique based on powder bed fusion technology that can produce near fully dense metal components. In SLM, a laser guided by a computer model is used to fully melt metal powder on a build platform layer by layer until a fully functional component is produced. The key advantages of SLM include reduced development time, design freedom, and little material waste.[1] Copper alloys have seen extensive use with additive manufacturing as a binder or infiltrant, but rarely as a principle component to take advantage of their high conductivity properties.[2] Although some work exists on electron beam melting of commercially pure copper, there is relatively little available research on electrical grade copper alloy systems fabricated by SLM.[3,4] Copper alloys have been difficult to process via SLM due to the poor laser absorption of copper, but increases in laser power in commercial SLM units present the opportunity to fabricate high density copper ANTHONY P. VENTURA, Loewy Graduate Fellow, MASASHI WATANABE, Associate Professor, and WOJCIECH Z. MISIOLEK, Loewy Professor and Chair, are with the Whitaker Lab, Materials Science and Engineering Department, Lehigh University, 5 East Packer Ave, Bethlehem, PA 18015. Contact email: [email protected] C. AUSTIN WADE, formerly Graduate Research Assistant with the Whitaker Lab, Materials Science and Engineering Department, Lehigh University, is now FEI Postdoctoral Research Fellow with the Materials Performance Centre, University of Manchester, Manchester, United Kingdom M13 9PL. GREGORY PAWLIKOWSKI and MARTIN BAYES, Principal Scientists, are with Tyco Electronics Corporation, a TE Connectivity Company, Harrisburg, PA 17111. Manuscript submitted March 23, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS A
alloy components.[5,6] Copper alloy components are of particular interest for electrical connector prototyping and fabrication of small production run components. Numerous studies have been conducted on other metal alloys that demonstrate unique processing parameters inherent in SLM that affect microstructural characteristics and the resulting mechanical properties.[7,8] Of particular importance is the high cooling rate, which can be up to 108 K/s.[9] As a result of this high cooling rate, there is a significant chance for the formation of metastable phases or fine solidification substructure. For example, in Ti-6Al-4V, the resulting SLM microstructure is fine acicular martensitic.[10] Austenitic stainless steels, such as 316L, retain their austenitic structure, exhibiting solidification substructures with cell spacing on the order of 1 lm or less.[11] Additionally, intermetallic phases and nonmetallic particles have been found at the melt pool boundary, occasionally serving as initiation sites for cracking and failure. These particles include those that normally occur in the alloy during solidification/segregation as well as defects retained from the source powder or the SLM processing atmosphere.[10,12] Nearly all metallic alloys cur
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