Microstructure and mechanical properties of a novel polycrystalline Ni3Al-based intermetallic alloy

A polycrystalline Ni3Al-based intermetallic alloy was successfully prepared via vacuum induction melting processing. Next, the microstructural evolution and mechanical properties of the intermetallic alloy were investigated by solution treatments at temperatures ranging from 1230 to 1290 degrees C. The results showed that the as-cast polycrystalline Ni3Al-based intermetallic alloy consisted of dendrite gamma+gamma ' with interdendritic distribution, matrix gamma ' phase, and eutectic gamma-gamma ', and the total volume fraction of gamma ' phase was similar to 83.2%. After solution treatment at 1270 degrees C, the size and morphology of the gamma ' phase changed and the secondary gamma ' phase precipitated in the gamma channel. The maximum room temperature yield strength, tensile strength and elongation reached 488 MPa, 686 MPa, and 5.2%, respectively. At 1100 degrees C, the high-temperature tensile strength of sample subjected to solution treatment at 1250 degrees C reached 203 MPa. It was found that solution treatment did not eliminate the incipient gamma '(m), resulting in the weaker interdendritic boundary area in the alloy. Moreover, noteworthy, alpha-Cr particles were found in the gamma(')m of the polycrystalline Ni3Al-based intermetallic alloy, revealing an orientation relationship such as [123]alpha-Cr||[123](gamma)' and (1-21)(alpha-Cr)||(11-1)gamma'. The alpha-Cr particles have the strengthening effect of second-phase particles through pinning dislocations, which can improve the high-temperature creep performance of the alloy.

Automated summary

A polycrystalline Ni3Al-based intermetallic alloy was successfully prepared via vacuum induction melting processing. The microstructural evolution and mechanical properties of the alloy were studied through solution treatments at different temperatures. The results showed changes in the size and morphology of the gamma ' phase after treatment and the precipitation of secondary gamma ' phase. The alloy exhibited high room temperature yield strength and tensile strength, and the presence of alpha-Cr particles improved its high-temperature creep performance.