The influence of spark plasma sintering temperatures on the microstructure, hardness, and elastic modulus of the nanocrystalline Al-xV alloys produced by high-energy ball milling

Abstract

• Synthesis of Al-V alloys from high-energy ball milling and spark plasma sintering. • Al-V alloys with far-from-equilibrium microstructure: V solubility 6 orders of magnitude higher than equilibrium value. • Elastic modulus of Al-V alloys is much higher than that of any commercial Al alloy. • Effect of spark plasma sintering temperature on the microstructure, hardness and elastic modulus of Al-V alloys. Al- x V alloys ( x = 2 at.%, 5 at.%, 10 at.%) with nanocrystalline structure and high solid solubility of V were produced in powder form by high-energy ball milling (HEBM). The alloy powders were consolidated by spark plasma sintering (SPS) employing a wide range of temperatures ranging from 200 to 400 °C. The microstructure and solid solubility of V in Al were investigated using X-ray diffraction analysis, scanning electron microscope and transmission electron microscope. The microstructure was influenced by the SPS temperature and V content of the alloy. The alloys exhibited high solid solubility of V―six orders of magnitude higher than that in equilibrium state and grain size < 50 nm at all the SPS temperatures. The formation of Al 3 V intermetallic was detected at 400 °C. Formation of a V-lean phase and bimodal grain size was observed during SPS, which increased with the increase in SPS temperature. The hardness and elastic modulus, measured using nanoindentation, were significantly higher than commercial alloys. For example, Al-V alloy produced by SPS at 200 °C exhibited a hardness of 5.21 GPa along with elastic modulus of 96.21 GPa. The evolution of the microstructure and hardness with SPS temperatures has been discussed.