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Titanium and Aluminum: Which Metal to Choose for 3D Printing?

Metal is currently one of the most common materials in additive manufacturing processes. It is not surprising that its outstanding performance makes it an ideal choice for applications that have stringent requirements for performance and durability. In this article, we will focus on two main metals used in 3D printing: titanium and aluminum. These are mainly used in processes such as laser powder bed melting (L-PBF) or concentrated energy deposition (DED). They are mainly provided in powder form, especially in industrial environments. We will compare their similarities and differences in order to better understand their characteristics and applications, as well as the advantages they provide in the manufacturing process.
Production and characteristics of titanium and aluminum
Titanium
Titanium is a material that does not exist as an element in nature and must be extracted from minerals such as rutile (TiO2) or ilmenite (FeTiO3). The extraction of pure titanium is a complex process involving multiple steps. The widely used method for producing pure titanium is the Kroll process, developed by American chemist William J. Kroll in 1940. This method involves reducing titanium dioxide (TiO2) with chlorine gas (Cl2) to produce titanium tetrachloride (TiCl4), which is then reduced with magnesium (Mg). Although the Kroll process is effective in producing pure titanium, it is an expensive process that requires a significant amount of energy. In addition, the high reactivity of titanium makes it difficult to obtain pure metal, so a sample with a purity of 99.9% is considered commercially pure titanium. That's why it usually combines with other elements to form alloys.
Titanium has many properties that make it widely used and useful in many industries. As mentioned earlier, it is usually used in alloy form, but due to its high biocompatibility, pure extracted titanium is used for certain applications, such as the medical industry. Its main characteristics are high mechanical strength, low density, excellent corrosion resistance, and high rigidity.
Development
The main titanium alloys used in 3D printing are:
Titanium 6Al-4V, Grade 5: This is * important and * common. Due to its high strength and durability, it is used in additive manufacturing. This alloy is made of titanium, aluminum, and vanadium, and can withstand high temperatures and corrosive environments.
Titanium 6Al-4V, grade 23: biocompatible, commonly used in medical implants and prostheses.
Titanium Beta 21S: Stronger and more resistant to oxidation and deformation than traditional titanium alloys. It is highly suitable for orthopedic implants and aerospace engine applications. Beta titanium is very popular in the field of orthodontics.
Cp Ti (pure titanium), grades 1 and 2: Due to its biocompatibility with the human body, titanium has a wide range of applications in the medical industry.
TA15: This is an alloy almost entirely composed of titanium, with the addition of aluminum and zirconium. Components made from this alloy are very sturdy and resistant to high temperatures, making them an ideal choice for manufacturing sturdy components in aircraft and engines. Compared to their strength, they are also very light.
Aluminum
Aluminum is a metal that achieves a perfect balance between weight and strength. In addition to corrosion resistance, it can also be welded. It is very rare in its pure state, so we will use it in the form of an alloy and together with metals that can improve its physical and mechanical properties, such as silicon and magnesium. Like titanium, two consecutive industrial processes make it possible to obtain materials in a pure state. In this process, called the Bayer process, alumina is obtained from bauxite. Wash and crush the ore, dissolve it in caustic soda, filter it to obtain pure aluminum hydroxide. Then heat to obtain alumina powder. In the second process, called the Hall-H é roult process, aluminum oxide is electrolytically reduced to obtain pure aluminum. Most beneficiation plants are built near mines to reduce the cost of ore transportation.
As mentioned above, aluminum alloys are more common than pure aluminum alloys and are used in many industrial applications. In addition, they also have a very good strength to weight ratio and excellent fatigue and corrosion resistance. They are also recyclable, thermally conductive, electrically conductive, and have low toxicity.
The main alloys used in aluminum 3D printing are:
AISi10Mg: This is a common alloy formed from silicon and magnesium. It can manufacture sturdy and complex parts, and is used to manufacture various objects such as casings, engine parts, and production tools.
Al2139: * Strong aluminum alloy, due to its light weight, high strength, and chemical resistance, is very suitable for industries such as automobiles. It has been used by organizations such as the United States Air Force, Mercedes Benz, and Airbus. The advantage of this material is that it is specifically designed for additive manufacturing and outperforms many other alloys on the market.
Al 7000 series: It is a powder alloy series with high tensile strength and low-temperature strength.
Al 6061 and Al 7075: * Recently, 3D manufacturers have achieved very good results using these two alloys. The tensile strength and hardness of 6061 are lower than those of 7075. On the other hand, 7075 has better impact resistance and warpage than 6061 aluminum.
A201.1: It is a part of the 200 series copper aluminum alloy, which is well-known for its durability. However, they are difficult to cast. These alloys are recommended for applications where strength to weight ratio is crucial, such as transportation and aerospace.
If we compare these two metals, what are the differences?
In terms of strength to weight ratio, titanium is the ideal choice when high strength and durability are required, which is why it is used in medical components and even satellite components. On the other hand, although aluminum is not as durable as titanium, it is lighter and cheaper. In terms of thermal performance, aluminum is very suitable for applications that require high thermal conductivity. On the other hand, titanium is highly suitable for applications in high-temperature environments, such as aerospace engine components, due to its high melting point. Both aluminum and titanium have excellent corrosion resistance. However, titanium has better biocompatibility than aluminum, which is why it is widely used in the medical field.
Material shape and 3D technology used
Shape
In most cases, titanium and aluminum are in powder form, although they can also be in wire form, such as the titanium or aluminum wires provided by Virtual Foundry or even Nanoe.
To use these metal 3D printed parts, it is necessary to first obtain alloy powder, which requires the use of two main techniques: plasma atomization or gas atomization. Plasma (ionized gas) atomization is a process that utilizes high temperature, energy and heat sources, inert media (such as argon), and high speed to atomize metals. This process produces high-quality wear-resistant powder. On the other hand, gas atomization uses air, argon, or helium as gases to decompose the molten material flow. This is a very effective process widely used for producing small spherical metal powders. The technology used to manufacture metal powders is important because it significantly affects the final performance of the parts.
The 3D technology used
To use titanium in 3D printing, various processes can be employed, such as laser powder bed melting (L-PBF), DED, or powder bonding. For processes related to aluminum, in addition to the processes already mentioned, there is another process, such as cold spraying, also known as cold spraying.
In the L-PBF additive manufacturing process, laser beams are used to heat powdered metal layer by layer to the melting point and construct objects. Titanium melts at very high temperatures (1600 ° C), so it is necessary to analyze the thermal and mechanical effects of the material before 3D printing. The melting temperature of aluminum is much lower (about 630 ° C), but aluminum has high reflectivity and thermal conductivity. Another interesting aspect of aluminum additive manufacturing is that it forms a natural oxide layer, and other metals later form a natural oxide layer at its edges, which means the presence of this thin layer on aluminum slows down the process.
Regarding DED, this is a very similar process to the previous one, but here the material melts while being deposited through a nozzle and can be manufactured in powder or wire form. Usually, this technology can achieve higher production speeds and lower unit volume costs.
In the case of adhesive spraying, the material is in the form of unmelted powder, but in order to make the particles adhere to each other, the adhesive is sprayed onto specific positions on the layer through a "print head". After printing, a sintering step is also required. The parts produced from 3D printers are very fragile and porous, requiring heat treatment to obtain the final mechanical properties.
In the cold spraying process, we also found metal materials in powder form, but because it does not need to be melted or fused in this case, cold spraying helps to avoid deformation due to heat and does not require a protective atmosphere.
Post processing
In order to obtain * results, one or more post-processing steps must be taken. There is no specific difference in post-treatment between titanium and aluminum, so the following steps apply to both materials. Due to the frequent use of titanium and aluminum in applications that withstand mechanical stress, micro sandblasting and shot peening are very useful. In * methods, small metal or ceramic balls are projected onto the surface of the part to generate controlled deformation of the surface layer of the part. This improves the adhesion of subsequent coatings and reduces the possibility of cracks and fractures. Shot blasting only removes surface materials, which can improve the appearance of parts, remove dirt and corrosion, and prepare the surface for subsequent coatings.
Another option is to combine metal printing with traditional manufacturing methods. CNC machining is a post-processing technique suitable for this purpose, as it ensures strict tolerances and the required surface finish. Especially when using DED technology, the surface of 3D printed parts is very rough because the metal melts directly during the extrusion process. That's why CNC machining is always needed to achieve smooth and well-defined surfaces.
Solution annealing is a heat treatment option that involves heating printed components to high temperatures and rapidly cooling them to alter the microstructure, thereby improving the material's ductility, i.e. the ability to deform under load before fracture. Generally speaking, this process can achieve better mechanical properties and is mainly used for aluminum parts.
When aluminum and titanium are used in so-called indirect 3D printing processes such as FDM or powder bonding, sintering is also necessary. After the printing phase is completed, the components must undergo a degreasing process to separate the adhesive polymer from the metal. Then heat the components in the sintering furnace to a certain temperature slightly below the melting temperature, which will solidify the final object. This results in a very low porosity of the part, as the cavity where the adhesive is located is sealed during processing, leading to compression.
Application Fields
The aerospace industry has discovered significant benefits from using titanium additive manufacturing. It is an ideal material for manufacturing aviation components such as jet engines and gas turbines, as it can significantly reduce the weight of structures subjected to high stress. An example of the application of titanium in additive manufacturing is Boeing's collaboration with Norsk Titanium to manufacture large structural components for the 787 Dreamliner. The technology used in this process is DED, which is said to be 50-100 times faster than powder systems and uses 25-50% less titanium than forging, potentially saving up to $3 million per aircraft.
If titanium is currently being used for space exploration through 3D printing, then the application of aluminum in industry has doubled. For example, Boeing uses aluminum alloy coated with nanoparticles to produce 3D printed parts during the cooling phase. This can weld extremely strong aluminum alloys without breaking when hot. The manufactured parts are lighter, allowing the aircraft to effectively use fuel and fly longer distances with the same amount of fuel.
Although the high price of titanium in the automotive industry may hinder its widespread use, we can see an increase in employment for titanium in this field, especially in the luxury car sector. Currently, 3D printing is used to manufacture parts where the weight/performance ratio is crucial. For example, Bugatti used SLM technology to print brake calipers for its titanium alloy brake system in just 45 hours, reportedly 40% lighter than traditional milled aluminum brake calipers. Although titanium components are lightweight, they also ensure their elasticity and temperature resistance. On the other hand, aluminum is more common in the automotive industry. Porsche uses 3D printing to manufacture high-performance aluminum pistons for its flagship 911 model GT2 RS. Thanks to this technology, a 700 horsepower twin turbo engine can achieve up to 30 horsepower in power and improve its efficiency. In addition, Porsche produced all aluminum 3D printed housings for electric drivetrains in 2020 and successfully passed all of the company's quality and load tests.
*Titanium has become a very interesting material in the medical industry due to its high strength, corrosion resistance, and biocompatibility, making it an ideal choice for orthopedic and dental implants. 3D printing can create porous structures that mimic bone textures, facilitating rapid healing and growth of bones and tissues. TrabTech in Türkiye uses titanium to make trabecular implants, such as hip joints. Aluminum is not as commonly used in the medical industry as titanium, but it can be used for orthopedic and dental applications.

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