TiVCrNb高熵合金显微结构及储氢性能研究

Study on microstructure and hydrogen storageperformance of TiVCrNb high entropy alloy

为探究TiVCrNb高熵合金的微观结构及储氢性能,采用真空电弧熔炼技术制备了TiVCrNb高熵合金。结果表明:合金由BCC结构相、FCC结构相和C15 Laves相组成。吸氢之后BCC结构相发生转变。合金粉末在623 K,4 MPa条件下进行活化后,分别在303、323、343 K、2 MPa氢压条件下进行第一次吸氢,最大吸氢质量分数分别为1.135%、1.014%、0.965%。随吸氢的温度降低,最大吸氢量增大,合金在较低温度下的吸氢性能较好。最大放氢质量分数分别为0.326%、0.360%、0.445%。放氢量与吸氢量相差较大。合金放氢不彻底,放氢性能较差。合金放氢的焓变与熵变如下:ΔH=22.470 32 kJ/mol;ΔS=72.941 96 J/mol·K。

In order to explore the microstructure and hydrogen storage performance of TiVCrNb high entropy alloy,vacuum arc melting technology was used to prepare TiVCrNb high entropy alloy.The results show that the alloy consists of BCC structural phase,FCC structural phase and C15 Laves phase.After hydrogen absorption,the BCC structural phase undergoes a transformation.The alloy powder is activated of 623 K and 4 MPa and the first hydrogen absorption is carried out on conditions of 303,323,343 K and 2 MPa hydrogen pressure respectively.The mass fraction of maximum hydrogen absorption are 1.135%,1.014%and 0.965%respectively.As the temperature of hydrogen absorption decreases,the maximum amount of hydrogen absorption increases,which shows the hydrogen absorption performance of the alloy is better at lower temperatures.The mass fraction of maximum hydrogen desorption are 0.326%,0.36%and 0.445%respectively.The difference between the hydrogen desorption capacity and the hydrogen absorption capacity is significant.The hydrogen desorption of the alloy is not complete and the hydrogen desorption performance is poor.The enthalpy and entropy changes of alloy hydrogen desorption are as follows:ΔH=22.47032 kJ/mol;ΔS=72.94196 J/mol·K.