Effect of Ti content on microstructure and properties of TixZrVNb refractory high-entropy alloys

This study aimed to investigate the microstructure and mechanical properties of TixZrVNb(x=1,1.5,2)refractory high-entropy alloys at room and elevated temperatures.The TiZrVNb alloy consisted of the body-centered cubic(bcc)matrix with a small amount of V2Zr phase.The Ti1.5ZrVNb and Ti2ZrVNb alloys exhibited a single-phase bcc structure.At room temperature,the tensile ductility of the as-cast alloys increased from 3.5%to 12.3%with the increase in the Ti content.The TixZrVNb alloys exhibited high yield strength at 600°C,and the ultimate yield strength was more than 900 MPa.Softening occurred at 800°C,but the ultimate yield strength could still exceed 200 MPa.Moreover,the TixZrVNb alloys displayed low densities but high specific yield strengths(SYSs).The lowest density of TixZrVNb alloys was only 6.12 g/cm^3,but the SYS could reach about 180 MPa·cm^3·g^−1,which is better than those of most reported high-entropy alloys(HEAs).

Microstructure and Mechanical Behavior of CrFeNi2V0.5Wx(x=0,0.25)High-Entropy Alloys

CrFeNi2V0.5Wx(x=0,0.25)alloys based on these parameters of mixing enthalpy(△Hmix,mixing entropy(△Smix,atomic radius difference(δ),valance electron concentration,and electronegativity difference(△χ)were designed and prepared.The microstructure and room-temperature mechanical behavior of both alloys were investigated.Compressive test results showed that the CrFeNi2V0.5W0.25 alloy had higher yield strength than that of the W-free CrFeNi2V0.5 alloy,although they all exhibited quite larger compressive plasticity(ε>70%).Compression fracture surface of CrFeNi2V0.5W0.25 alloy revealed a ductile fracture in the face-centered cubic(FCC)phase and a brittle-like fracture in theσphase.Moreover,tensile test results indicated that the CrFeNi2V0.5W0.25 alloy exhibited excellent mechanical property with an ultimate tensile strength of 640 MPa and a high tensile elongation of 15.7%.The tensile deformation mode of the FCC phase in the CrFeNi2V0.5W0.25alloy is dominated by planar glide,relating to dislocation configurations,high-density dislocations,and dislocation wall.Therefore,dislocation slip plays a significant role in tensile deformation of CrFeNi2V0.5W0.25 high-entropy alloy.The higher strength of CrFeNi2V0.5W0.25 alloy is predominantly due to the solid solution strengthening of W element andσphase precipitation strengthening.Combination of the higher tensile strength and plasticity suggests that the CrFeNi2V0.5W0.25 alloy can be a promising aerospace material.