Fabricating Lightweight Ti-6Al-4V and Other Metallic Foams Using Electron Beam Melting

Metal foams are used in numerous applications to provide reduced weight, mechanical damping, vibration absorption, flow filtering, heat transfer, and more.  Metal foams are typically manufactured by melt gas injection, gas-releasing particle decomposition, and casting using a wax precursor as a template as well as other techniques.  By taking advantage of newly-developed Additive Manufacturing (AM) technologies such as Electron Beam Melting (EBM), metal foam structures can be directly fabricated from virtually any powder metal in a layer-by-layer additive manufacturing process.  Using this approach, entirely new applications may emerge that enable foams of virtually any metal system to be directly fabricated from digital data.  In this work, a method for designing and manufacturing customized open and closed cellular metal foam structures has been developed.  The method consists of using computed tomography (CT) to scan existing foams manufactured using traditional processes to create various foam geometries in CAD.  In CAD, the geometry can be manipulated to vary the geometric characteristics and to integrate foam structures with other designs.  The method allows for customizable designs with gradient and controlled properties such as density, strength, and hardness.  To demonstrate the process capabilities and material systems that are not presently used in foams, a variety of foam geometries were fabricated out of Ti-6Al-4V and CoCrMo.  Characterization of the foams was performed through mechanical testing in tension, compression and impact.  Results showed that the foam structures are suitable for load bearing applications.  This method using AM and powder metals can lead to many new custom applications.