Enhancement of mechanical properties of LDEDed IN738LC alloy by solid-solution strengthening coupled with precipitation-strengthening

The high cracking susceptibility is the major obstacle to the wide application of high gamma '-phase nickel -based superalloys in additive manufacturing. It is especially important to explore the effects of alloying elements during the nickel -based superalloys and establish a new alloy design criterion. In this work, a new nickel -based superalloys with crack -free and low porosity was fabricated by adjusting the content of solid -solution and precipitating elements of Inconel 738LC (IN738LC) alloy utilizing laser directed energy deposition (LDED) technology, achieving an increase in strength and ductility simultaneously. The newly developed nickel -based superalloys maintain a high content of gamma '-phase and display substantial fine bulk MC carbides, resulting in higher strength (UTS: 1461 MPa, YS: 1105 MPa) and elongation (EL: 12.9%). After heat treatment, extensive long -stripes of M23C6 carbides were detected in the IN738LC sample, which led to poor tensile properties at high temperature (900 degrees C). However, due to the finer gamma ' phase uniformly distributed in the matrix, the developed new nickel -based superalloys exhibits optimal tensile properties (UTS: 593 MPa, YS: 475 MPa) and ductility (9.4%) at 900 degrees C. This approach can provide guidance for the design of high gamma '-phase nickel -based superalloys for additive manufacturing starting from elemental powders.