With the ability to fabricate fully dense, near-net shape, metal components with technologies like Electron Beam Melting and Laser Melting, there is an increased interest in developing process parameters for new materials. This includes existing metals and alloys as well as new exotic alloys that may be difficult to process using traditional methods. Our ITAR compliant lab has been developing process parameters for the Arcam since 2003 when we purchased the very first commercially available Arcam system. Many types of metal powder can be melted using the Arcam system, if you have a material that you are interested in, please give us a call. A feasibility study can usually be completed with a small amount of material. Below is a brief description of such materials.
This was one of the first materials that we worked with back in 2003. GRCop-84A high temperature copper alloy that was developed at the NASA Glenn Research Center for use in rocket engines. While this material exhibits many desirable properties such as high strength at high temperature, casting the material results poor, segregated microstructure. Utilizing powder metallurgy can result in a more homogenous material, typically at the expense of part complexity. However in a relatively short period of time we were able to fabricate demonstration components from the material using the Arcam process.
Aluminum and Aluminum Alloys
In the past few decades, there has been a steady trend of replacing ferrous alloys with aluminum alloys. The main advantages of aluminum alloys are their reasonable strength to weight ratios and their low melting points, which makes them more energy efficient to process. This material also possesses other desirable qualities such as high conductivity, ductility, machinability and toughness. Aluminum alloys also easy to recycle due to their low melting points. Their recycling also requires far less energy than that required for extraction of aluminum from ore. The development of better aluminum casting alloys has resulted in almost a complete migration to aluminum engine blocks in the passenger car markets. The research related to layered manufacturing of aluminum has largely been supported by the aerospace industry. The components used in this industry can be classified as low volume-high reliability, many a times the demand being as low as a single unit. The other, more futuristic project pursued by the aerospace industry is the deployment of additive systems during space missions for on demand fabrication. To date our research has focused on 2024, 6061 and 7075 alloys.
Nickel Super Alloys (Inconel 625, Inconel 718, Mar M-247)
Nickel super alloys are valued for their strength at high temperatures and corrosion resistance. Additive manufacturing offers a unique opportunity for near net shape utilization of these expensive alloys coupled with freedform of design capabilities. These alloys have been the subject of a great deal of our research. Since 2005 we have developed and optimized EBM process parameters for alloys such as Inconel 718, Inconel 625 and Mar M247.
This was one of the early materials that we conducted research with starting in 2004. Gamma phase TiAl (γ-TiAl) has many properties that are of particular interest to the aerospace industry for the fabrication of blades used in high speed gas turbine engines. For instance, at high temperatures γ-TiAl exhibits low density and retention of specific strength, modulus, creep and corrosion resistance. However, despite the desirable characteristics of γ-TiAl, one of the major barriers to its widespread use has been associated with difficulties in processing. Typical problems in processing include porosity, chemical inhomogeneities, and poor microstructure (the properties of γ-TiAl are highly microstructure dependent). For extrusion and forging, the manufacturing costs are extremely high, the internal microstructure is very difficult to control and most heterogeneities can be traced back to the source ingots used. Casting of γ-TiAl has not been able to produce satisfactory results either. The high reactivity of the material coupled with high porosity has resulted in scrap rates as high as 80%.
High Purity Copper (OFHC)
More recently, there has been growing interest in the use of additive manufacturing for the fabrication of components of copper and copper alloys for a wide variety of applications such as; optimized mesh structures for high-surface area heat exchangers, electrodes for spark erosion tools with internal cooling channels, and, recently, the fabrication of novel radio frequency (RF) structures. Additive manufacturing facilitates the fabrication of fully dense, near net shape copper structures with optimized internal cooling channels without the usual constraints associated with traditional manufacturing methods.
Pure Reactor Grade Niobium
Superconducting Radio Frequency (SRF) accelerators are now considered the device of choice for many applications in high energy and nulcear physics. The additive nature of the EBM process eliminates many of the traditional manufacturing constraints allowing design of complex geometries such as internal conformal cooling channels for optimized thermal management. One of the key concerns regarding the manufacture of SRF components is the requirement for high purity materials. EBM produced samples exhibit a relatively sharp transition from the normal to the superconducting state, with a spread over a range of < 0.1K with about 1/2 of the RRR value of bulk material.
NiTi material exhibits some very interesting properties, including shape memory and superelacticity. There are two phases: martensitic (the low temperature compliant phase) and austenitic (the high temperature stiffer phase). When heated above a critical temperature (the austenitic start or As temperature), NiTi undergoes an internal phase transformation in which the material changes from a compliant martensitic phase to a rigid austenitic phase. This phase transition temperature is a function of material composition and heat treatment processes during manufacturing. Using the EBM process we have demonstrated the ability to fabricate solid and network structures using Nitinol.