Ti-Hf合金的结构和吸氘热力学性质

Structure and Thermodynamic Aspect of Ti-Hf Alloys and Their Deuterides

采用磁悬浮法制备了4种TiHfx,(x=0.13,0.26,0.52,1.03)二元合金。利用X射线衍射技术对纯钛、纯铪和4种成分Ti-Hf二元合金吸氘前后的物相结构、晶胞参数和吸氘特性进行了研究。Ti-Hf合金吸氘前均为六方密堆结构,饱和吸氘后形成较单一的面心四方ε相氘化物。随Hf含量增加,Ti-Hf合金及其ε相氘化物的晶胞参数均呈增大趋势。压强-组成等温线显示,Hf含量增加将导致氘化物室温平衡压升高,Ti-Hf合金热力学性质趋近于H-Hf体系,Hf对Ti-Hf合金氘化物热力学性质起主导作用。Hf掺杂显著降低了Ti吸氘的体膨胀,从而有望缓解由于体胀导致的氢脆现象。

Magnetic levitation melting technique was utilized to prepare a set of Ti-Hf binary alloys, TiHfx（x=0.13, 0.26, 0.52, 1.0）. The phases, lattice parameters and deuterating reaction features of pure Ti, pure Hf and Ti-Hf alloys were investigated before and after their deuterides formation by XRD. Ti-Hf alloys have a hexagonal close packed crystal structure and their saturated deuterides include only ε-phase with a face-centered tetragonal （fct） structure. The lattice constant of Ti-Hf alloys and their deuterides gradually increase with increasing propotion of Hf in the alloys. From the P-C isotherms, it could be found that the equilibrium pressure of the deuterides at room temperature rises when Hf/Ti ratio increases in Ti-Hf alloys. The thermodynamic characteristics of Ti-Hf alloys deuterides are closer to those of H-Hf system than H-Ti system, which means that its the Hf metal that dominates the thermodynamic feature of Ti-Hf alloys. Hf doping in Ti will remarkably reduce the lattice expansion, which may make the H-Ti system embrittlemental.