| Summary: | L1<sub>2</sub>-type Ni<sub>3</sub>Al alloys containing vanadium are potential candidates for solid-solution and age-hardenable alloy systems, according to the Ni<sub>3</sub>Al-Ni<sub>3</sub>V pseudo-binary phase diagram. Therefore, herein, variations in the microstructure and mechanical properties of Ni-13 at.% Al-12 at.% V-50 ppm B alloy during isothermal aging were investigated. Alloy specimens were solution-treated at 1323 K for 48 h, quenched in water, and aged at 1073 K to 1173 K. The quenched specimens exhibited a single phase of Ni<sub>3</sub>Al (L1<sub>2</sub> structure derived from Al (fcc) structure), while in the aged specimens, numerous fine disk-shaped precipitates identified as Ni<sub>3</sub>V (D0<sub>22</sub> structure from orthorhombic structure) were formed on {001} planes of the Ni<sub>3</sub>Al matrix. The size of the disk-shaped Ni<sub>3</sub>V precipitates increased gradually with increasing aging period. The hardness and strength of the specimens increased initially during aging at 1073 K to 1173 K, reached a maximum, followed by a subsequent decrease. The age-hardening behavior observed for the specimens can be explained in terms of precipitation of the fine disk-shaped Ni<sub>3</sub>V precipitates in the Ni<sub>3</sub>Al matrix. Furthermore, the peak-aged specimens exhibited an increase in yield strength with increasing testing temperature, similar to other L1<sub>2</sub>-type intermetallic alloys.
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