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

A polycrystalline Ni 3 Al-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 °C. The results showed that the as-cast polycrystalline Ni 3 Al-based intermetallic alloy consisted of dendrite γ+γ′ with interdendritic distribution, matrix γ′ phase, and eutectic γ–γ′, and the total volume fraction of γ′ phase was ∼83.2%. After solution treatment at 1270 °C, the size and morphology of the γ′ phase changed and the secondary γ′ phase precipitated in the γ channel. The maximum room temperature yield strength, tensile strength and elongation reached 488 MPa, 686 MPa, and 5.2%, respectively. At 1100 °C, the high-temperature tensile strength of sample subjected to solution treatment at 1250 °C reached 203 MPa. It was found that solution treatment did not eliminate the incipient γ′ m , resulting in the weaker interdendritic boundary area in the alloy. Moreover, noteworthy, α-Cr particles were found in the γ′ m of the polycrystalline Ni 3 Al-based intermetallic alloy, revealing an orientation relationship such as [123] α-Cr ∥[123] γ' and (1–21) α-Cr ∥(11–1) γ'. The α-Cr particles have the strengthening effect of second-phase particles through pinning dislocations, which can improve the high-temperature creep performance of the alloy. • A vacuum induction melting polycrystalline Ni 3 Al-based intermetallic alloy was investigated for its room temperature and 1100 °C high temperature mechanical properties, and microstructure. • Nano-sized α-Cr particles formed in the γ′ phase on the Al-rich and Ni-poor side, the orientation relationship of [123] α-Cr ∥[123] γ' and (1–21) α-Cr ∥(11–1) γ' between the precipitates α-Cr and γ′-matrix. • The inter-dendrite boundary is the weakest point of the alloy. [ABSTRACT FROM AUTHOR]