硼含量对Ni_3(Si,Ti)合金在空气中环境氢脆的作用

Effect of B Content on Environmental Hydrogen Embrittlement of Ni_3(Si,Ti) Alloys

研究了硼含量对Ni_3(Si,Ti)合金的相组织、合金在真空和空气环境中的力学性能及环境氢脆敏感性的作用。结果表明,Ni_3(Si,Ti)合金的晶粒尺寸随合金中硼含量增加而降低;微量(CB≤0.02%)硼原子有效提高了合金在空气中的力学性能,与无硼Ni_3(Si,Ti)合金相比,添加0.005%硼可使合金在空气中的延伸率提高198%。当硼含量为0.02%时,合金在真空和空气中的抗拉强度和延伸率均达到最大值,合金的断口形貌为完全韧窝状断口,合金的氢脆因子降至1.5%,硼原子基本上抑制了Ni_3(Si,Ti)合金在空气中的环境氢脆。当合金中硼含量大于0.02%后,Ni_3(Si,Ti)合金中析出Ti B2相。而且,随着硼含量的(CB>0.02%)增加,Ti B2相的数量随之增多,合金在真空和空气中的力学性能随之降低,在空气中的氢脆因子随之升高,合金在空气中的断口形貌由完全韧窝状断口又转变为穿晶与解理的混合断口。

The effect of boron on the microstructure of Ni3 （Si, Ti） alloy, the mechanical properties and the environmental hydrogen embrittlement of the boron doped Ni3 （Si, Ti） alloy were investigated in this paper. The results show that the grain size of the alloy decreased with increasing boron content doped in the Ni3 （Si,Ti） alloy. The mechanical properties of the alloy in air were improved effectively by trace boron, the elongation of Ni3 （Si, Ti）-0. 005% B alloy increased by 198% compared with the boron-free Ni3 （Si,Ti） alloy when tested in air. The strength and elongation of Ni3 （Si, Ti）-0.02% B alloy reached maximum when the alloy tested in vacuum and air, and the fracture surface of the alloy was completely dimple fracture. The hydrogen embrittlement factor of Ni3 （Si, Ti）-0.02% B alloy was only 1.5% , i. e. , the environment hydrogen embrittlement of Ni3 （Si, Ti） alloy in the air was suppressed completely by boron. However, when the boron content in the alloy was more than 0. 02% , TiB2 phase preeipitateed in the Ni3 （Si,Ti） alloy. Moreover, the amount of TiB2 phase increased with the increase of boron content （ CB ≥0. 02% ） , resulting in that the mechanical properties of the alloy decreased in vacuum and air, the hydrogen embrittlement factor of the alloy increased and the fracture mode of the alloy changed from full transgranular to mixed fracture of intergranular and transgranular.