Tantalum and tantalum alloys are challenging to weld and machine. Their high melting points and reactions with gases present challenges to fabricators. While tantalum and Ta-2.5%W are different from other alloys, their fabrication is not necessarily difficult if the correct procedures are followed.
Successful machining of tantalum requires experience. High speeds and low cooling rates generate heat that causes the tantalum to react with carbon, oxygen, and hydrogen to form extremely hard particles. These particles quickly dull the tool and cause more heat to be generated. Tantalum is also a soft, colloidal material that tends to gel. To compensate for these characteristics, very slow rotational speeds should be used and large amounts of coolant are required. Water-soluble oils are suitable for most cooling; fluorocarbon lubricants can provide additional benefits when needed.
The cleanliness of the tantalum surface can greatly affect weld quality. Hydrocarbons (oils) react during welding to form brittle hydrides and carbides. Tantalum surfaces should be degreased prior to welding.
Other methods such as electron beam welding (EBW) and plasma arc welding (PAW) may also be used. The same precautions apply as for preventing hot surfaces from being exposed to air.