High-pressure and multi-atmosphere assisted SLM gradient material preparation method and aluminum-lithium alloy coating

A high-pressure and multi-atmosphere assisted selective laser melting (SLM) gradient material preparation method, comprising the following steps:

• continuously injecting a first gas mixture into an airtight working box to maintain a high-pressure environment in the airtight working box, wherein the first gas mixture is a gas mixture of an inert gas and a carbon-containing active gas;
• and irradiating aluminum-lithium alloy powder laid on a surface of a substrate with a laser to form a micro-melt pool, and enabling molten materials in the micro-melt pool to react with the carbon-containing active gas to form a carbide-doped first gradient aluminum-lithium alloy coating;
• discharging the first gas mixture out of the airtight working box;
• continuously injecting a second gas mixture into the airtight working box to maintain a high-pressure environment in the airtight working box, wherein the second gas mixture is a gas mixture of an inert gas and a carbon and nitrogen-containing active gas;
• irradiating aluminum-lithium alloy powder laid on a surface of the carbide-doped first gradient aluminum-lithium alloy coating with the laser to form a micro-melt pool, and enabling molten materials in the micro-melt pool to react with the carbon and nitrogen-containing active gas to form a carbide and nitride-doped second gradient aluminum-lithium alloy coating;
• and
• discharging the second gas mixture out of the airtight working box;
• continuously injecting a third gas mixture into the airtight working box to maintain a high-pressure environment in the airtight working box, wherein the third gas mixture is a gas mixture of an inert gas and a nitrogen-containing active gas;
• irradiating aluminum-lithium alloy powder laid on a surface of the carbide and nitride-doped second gradient aluminum-lithium alloy coating with the laser to form a micro-melt pool, and enabling molten materials in the micro-melt pool to react with the nitrogen-containing active gas to form a nitride-doped third gradient aluminum-lithium alloy coating,
• wherein, a pressure of the high-pressure environment created by the first gas mixture is P1, a pressure of the high-pressure environment created by the second gas mixture is P2, a pressure of the high-pressure environment created by the third gas mixture is P3, and P1>P2>P3;
• the pressure P1 of the high-pressure environment created by the first gas mixture is 3.5-5.0 MPa, the pressure P2 of the high-pressure environment created by the second gas mixture is 2.0-2.5 MPa, and the pressure P3 of the high-pressure environment created by the third gas mixture is 1.0-1.5 MPa.