球磨时间对软第二相韧化Cr_2Nb基复合材料组织与性能的影响

Effects of Ball Milling Time on Microstructure and Properties of Soft Second Phase Toughening Cr_2Nb Based Composite

采用机械合金化+热压工艺制备了含Laves相的Cr2Nb基复合材料,研究了Cr、Nb元素粉经不同球磨时间后在1250℃×30 min热压工艺下所获得Cr/Cr2Nb复合材料的组织和性能。结果表明,经20 h以上高能球磨的Cr-25Nb粉末在热压后可以制备出含高致密度的Laves相的Cr2Nb基复合材料。高能球磨40 h的Cr-25Nb试样的组织均匀细小,Laves相与软第二相间隔分布。其致密度高达99.2%,接近全致密,维氏硬度为8.93 GPa,抗压强度、屈服强度和塑性应变分别达到2153 MPa、2062 MPa和8.42%。与传统熔铸工艺相比,MA+热压方法制备的Laves相Cr2Nb基复合材料的强度及塑性都有显著提高,充分实现了细晶和软第二相综合增韧的效果。

Cr2Nb based composite with Laves phase was prepared by mechanical alloying followed by hot pressing. The microstructure and properties of Cr/Cr2Nb composite, which was made by hot pressing at 1250℃for 30 min after different time ball-milling of the powders with chromium and niobium elements, was studied. The results show that the Cr2Nb based composite with full-dense Laves phase is obtained by hot pressing via over 20 h ball-milled powders. The 40h ball-milled Cr-25Nb sample has homogeneous and fine microstructure with uniformly spaced Laves phase and soft second phase. Moreover, the sample has a relative density of 99.2%, a Vickers hardness of 8.93 GPa, a compress strength of 2153 MPa, yield strength of 2062 MPa and strain of 8.42%. Compared with Cr/CFENb composite prepared by arc-melting, the strength and ductility of the alloy increase greatly, the effect of fme grain toughening and soft second phase toughening has been fully realized.