合金元素对Laves相增强Nb基合金的相组成

采用机械合金化与热压烧结工艺制备了添加合金元素V和Fe的Laves相增强的Nb基复合材料。研究了添加质量分数4%V和Fe的Nb/NbCr2-4.0V和Nb/NbCr2-4.0Fe配比成分的元素粉,经MA20h后在1250℃热压30min所获得的Nb/NbCr2合金的组织和性能。结果表明:在热压过程中原位合成出细小弥散分布的三元Laves相Nb(Cr,V)2和Nb(Cr,Fe)2,并且V和Fe原子只占据Laves相中的Cr原子位置。制备出的Laves相增强Nb基合金接近全致密,组织细小均匀,晶粒尺寸小于500nm。Nb/NbCr2-4.0V和Nb/NbCr2-4.0Fe合金的断裂韧性分别达到5.3和6.3MPa·m1/2,其中Nb/NbCr2-4.0Fe合金不仅抗压强度达到2256MPa,其屈服强度和塑性应变也分别达到2094MPa和6.03%。

Effects of Alloying Element Additions on the Phase Transformation and Mechanical Properties of Laves Phase Reinforced Nb Matrix Composites

The Laves phase reinforced Nb matrix composite materials with V and Fe additions were prepared by mechanical alloying and reactive hot pressing. Microstructures and properties were investigated of Nb/NbCr2 alloys prepared from 20 h mechanically alloyed powders of Nb/NbCr2-4.0V and Nb/NbCr2-4.0Fe stoichiometric compositions by hot pressing at 1250 °C for 30 min. The results indicate that the fine dispersed ternary Laves phase Nb(Cr,V)2 and Nb(Cr, Fe)2 are synthesized in the Nb matrix by the in-situ reaction synthesis technique during hot pressing. In the ternary Laves phase V and Fe atoms preferentially occupy the Cr sites. The prepared Laves phase reinforced Nb matrix alloys with fine and uniform microstructures are nearly full-dense, and their grain sizes are less than 500 nm. The Nb/NbCr2-4.0V and Nb/NbCr2-4.0Fe alloys have fracture toughnesses of 5.3 and 6.3 MPa·m1/2 respectively. Furthermore, the Nb/NbCr2-4.0Fe alloy has a yield strength of 2094 MPa, compressive strength of 2256 MPa and plastic strain of 6.03%