The Uniweld P3KH9 Self-Fluxing Aluminum Joining Build-Up Aluminum Alloy is a self-fluxing aluminum alloy that is designed to join aluminum parts together without the need for a flux. This alloy is also resistant to corrosion and can be used to create a variety of parts, including aircraft parts and components. The Uniweld P3KH9 Self-Fluxing Aluminum Joining Build-Up Aluminum Alloy is a self-fluxing aluminum alloy that is designed to join aluminum parts together without the need for a flux. This alloy is also resistant to corrosion and can be used to create a variety of parts, including aircraft parts and components.