硼对有序态Ni_3Fe合金氢气环境中氢脆敏感性的影响  

Effect of boron on the environmental embrittlement of ordered Ni_3Fe alloys in gaseous hydrogen

作　　者：马杰[1] 陈业新[1] Liu C T 

机构地区：[1]上海大学材料研究所,上海 200072 [2]田纳西大学材料科学与工程系,美国,TN37996-2200

出　　处：《南京大学学报（自然科学版）》2009年第2期241-247,共7页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金(50371050,50671057)

摘　　要：硼含量(0.01～0.06wt.%B)对有序态Ni-24at.%Fe合金在真空和氢气环境中的力学性能有较大的影响,对有序态Ni3Fe合金在氢气环境中的氢脆敏感性也有较大的作用.研究结果表明,加硼后有序Ni3Fe合金的晶粒尺寸得到细化,材料的强韧性提高;硼有效抑制了有序态Ni-24at.%Fe合金在氢气环境中的氢脆.当合金中硼含量为0.06wt.%时,有序态Ni3Fe合金在氢气环境中的氢脆因子(IH2)为1%,与无硼Ni3Fe合金相比,合金氢脆因子的下降幅度达到98.7%.在氢气环境中拉伸时,无硼有序态Ni3Fe合金的断口形貌为完全的沿晶断口;随着Ni3Fe合金中硼含量的增加,合金断口形貌中的沿晶断口所占比例逐渐减少;当合金中的硼含量大于0.03wt.%后,断口形貌变为全部塑性的韧窝状断口.合金的断口形貌变化表明,有序态Ni3Fe合金中的硼提高了合金的晶界强度.硼对有序态Ni3Fe合金在氢气环境中力学性能和氢脆因子的作用变化表明,硼对有序态Ni3Fe合金中由氢气诱发的环境氢脆有较强的抑制作用.In this paper the tensile properties of an ordered Ni-24at. %Fe alloys doping with various boron content （0.01 -0.06wt. %） when tested in vacuum and in gaseous hydrogen have been investigated. The results show that the grains are refined, ductility and strength are increased, and the He-induced embrittlement of the alloy in gaseous hydrogen is suppressed substantially when boron is doped in Ni-24at. %Fe alloys. The hydrogen embrittlement fac- tor （IH2 ） of the ordered Ni3Fe alloy decreases sharply with the increment of boron content in the alloy. Iw2 of the ordered Ni3 Fe alloy decreases linearly when boron content increases from 0 to 0.03wt. %, then the rate slows when boron content increases continuously. Compared with B-free Ni3Fe alloy, Iu2 of the ordered NiaFe doping with 0.06wt. % B decreases by 98.7%. The boron free ordered Ni：~Fe displays the brittle fracture （intergranular frac- ture） when tested in gaseous H2. The parts of dimple rupture （transgranular fracture） in the fractograph increase gradually with increasing the concentration of boron in the alloy when tensile tests were conducted in gaseous hydro- gen. When the boron content is larger than 0.03wt. %, the ordered Ni3Fe alloy exhibits the ductile fracture, i. e. , with 100% transgranular fracture. The observed fraetographs are quite consistent with the elongation and ultimate tensile strength of the alloy. The changes of fractographs show that boron added in the alloy enhances the gain boundary strength and changes the mode of fracture of the ordered Ni：~ Fe alloy when tested in gaseous H2. The ex perimental results of this paper reveal that the boron atoms segregation to the grain boundaries can suppress the grain boundary fracture and dramatically improve the tensile ductility of the ordered Ni3 Fe alloy at room tempera- lure. The boron doping can effectively suppress the H2-induee embrittlement of the ordered Ni3Fe intermetallics.

关 键 词：Ni3Fe金属间化合物 环境氢脆 硼含量 

分 类 号：TG172[金属学及工艺—金属表面处理] TG146.1[金属学及工艺—金属学]