Thermal stability of the grain structure in the W-2V and W-2V-0.5Y2O3 alloys produced by hot isostatic pressing

Abstract

Highlights:-W-2V and ODS W-2V-0.5Y 2 O 3 alloys have been produced following a powder metallurgy route.-Grain microstructure and microhardness have been studied after isothermal treatments in vacuum.-Both alloys exhibit a duplex grain size population: a submicron-sized grain and a coarse grained one. Keywords: W alloys, Oxide dispersion strengthened W alloys, Grain growth, Recovery, Microhardness Abstract: W-2V and ODS W-2V-0.5Y 2 O 3 alloys have been produced following a powder metallurgy route consisting of mechanical alloying and a subsequent high isostatic pressing HIP at 1573 K. The grain microstruc-ture and microhardness recovery of the alloys have been studied in samples subjected to isothermal treatments in vacuum in temperature range 1073-1973 K. Both alloys exhibit a duplex grain size distri-bution consisting of a submicron-sized grain and a coarse-grained population. It has been found that the Y 2 O 3 addition inhibits growth of the coarse grains at T < 1973 K. Submicron grain growth, with activa-tion enthalpy of 1.9 and 2.49 eV for W-2V and W-2V-0.5Y 2 O 3 , respectively, was observed at T ≥ 1573 K. It resulted that the rate constant for grain growth is 30 times higher in W-2V-0.5Y 2 O 3 than in W-2V. The considerable enhancement of the microhardness in the W-2V-0.5Y 2 O 3 appears to be associated to dispersion strengthening.

The role of vanadium additive in the activated sintering and shrinkage rate of tungsten–vanadium alloys

“…The addition of V can constrain the grain growth of W. 17 This phenomenon can be found in Figs. 2(a)-2(c), where the W grains are gradually decreased.…”

Study on substitution of Ni with Ni3Al on structure and properties of W–6Ni3Al–4Co alloys by two-step sintering process

“…The phase determination was performed for sintered samples using x-ray Diffractometer (D8 ADVANCEX). Micro hardness tester (HVS-1000) was used to evaluate the average hardness of W-6Ni 3 Al-4Co alloys. The loads and holding times were 100 g and 20 s, respectively.…”

“…High density tungsten alloys can be used as functional materials, such as high-voltage contact and heating unit of electron microscope, because of good conductivity of heat and electricity [1][2][3]. Owing their superb mechanical properties, they can also be used as structural materials, such as bullet core, gyroscope, and first wall of nuclear reactor [4][5][6].…”

Influence of vanadium precursor powder size on microstructures and properties of W–V alloy

“…Thus large refinement of W grains can be achieved by adding submicron V precursor powder. Furthermore, the microstructural analysis based on SEM images of W-V alloy by Martinez et al [16] demonstrated a duplex grain size distribution consisting of two grain families: 1) fine submicron-sized grains; 2) coarse grains N 1 μm, which were ascribed to the discontinuous dynamical recrystallization occurred during the HIP sintering. In our study, only fine grains are observed, thus SPS can avoid the discontinuous dynamical recrystallization.…”

“…The result of microstructure analysis has shown V pools present in W-V and W-V-La 2 O 3 , which suggests that their present milling conditions are not able to promote the perfect dissolution of V in W. Our previous studies [13,14] also report that it is rather difficult to reduce its powder size by milling conditions since V possesses high ductility. In most previous studies a larger V precursor powder of micron size has been used [9,12,15,16]. However the addition of submicron size V precursor powder in W has not been reported.…”