Abstract
L12-type Ni3Al alloys containing vanadium are potential candidates for solid-solution and age-hardenable alloy systems, according to the Ni3Al-Ni3V 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 Ni3Al (L12 structure derived from Al (fcc) structure), while in the aged specimens, numerous fine disk-shaped precipitates identified as Ni3V (D022 structure from orthorhombic structure) were formed on {001} planes of the Ni3Al matrix. The size of the disk-shaped Ni3V 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 Ni3V precipitates in the Ni3Al matrix. Furthermore, the peak-aged specimens exhibited an increase in yield strength with increasing testing temperature, similar to other L12-type intermetallic alloys.
Highlights
Ni3 Al-based alloys offer several advantages such as high melting point, excellent mechanical properties at high temperatures, high thermal conductivity, good oxidization resistance, and low density, which are prerequisites for the vehicle components used in high-temperature applications such as engines and turbine blades
With the development of novel high-temperature materials, Ni3 Al intermetallic compounds with the L12 structure derived from the A1 structure play an important role as the primary phase for single-phase Ni3 Al-based alloys, [1,2,3,4,5,6,7,8,9,10,11] Ni3 Al/Ni3 V for dual two-phase alloys [12,13,14,15], and the dispersive strengthening phase for Ni-based superalloys [16,17,18,19,20]
Ni3 Al-based alloys suffer from poor ductility at ambient temperature and fundamental and practical efforts to improve the strength at low and high temperatures and the intrinsic deformability of the Ni3 Al phase have been of significant interest
Summary
Ni3 Al-based alloys offer several advantages such as high melting point, excellent mechanical properties at high temperatures, high thermal conductivity, good oxidization resistance, and low density, which are prerequisites for the vehicle components used in high-temperature applications such as engines and turbine blades. Alloys based on the Ni3Al-Ni3V pseudo-binary alloy system should be potential solid-solution supersaturates at a eutectoid temperature, as shown in Figure 1 [33]. It is expected that age-induced and aged-hardenable alloys, because vanadium dissolves well in the L12 Ni3Al phase and largely hardening due to the precipitation of hard Ni3 V with the D022 structure can improve the strength supersaturates at a eutectoid temperature, as shown in Figure 1 [33]. Ni3Al through motion the fine was dispersion of age-induced precipitates, as wellWe as in thewematrix, by which thealloys dislocation hindered even at high temperatures. Through the dissolution of solutes in the matrix, by which the dislocation motion was hindered even examined variations in the microstructure and mechanical properties during isothermal aging for a at high temperatures. During isothermal aging for a Ni3Al alloy containing a large amount of vanadium
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