Mn微合金化对Ti-Al-Mo-Zr-Fe-B合金组织演变和力学性能的影响

Effect of Mn Microalloying on Microstructure Evolution and Mechanical Properties of Ti-Al-Mo-Zr-Fe-B Alloy

摘要:

通过OM、EBSD和TEM等研究了Mn微合金化对新型近α Ti-Al-Mo-Zr-Fe-B合金微观组织和力学性能的影响。结果表明：添加0.5%（质量分数）的Mn元素可以将合金的铸态微观组织从3.28 μm细化到2.65 μm，使其抗拉伸强度从882 MPa提高到966 MPa，但延伸率从7.8%下降到5.1%。锻造后的2种合金的晶粒尺寸趋于一致，微观组织趋于等轴化且Mn微合金化后的组织更加均匀。锻造后，Ti-Al-Mo-Zr-Fe-B合金的抗拉伸强度和延伸率增加到966 MPa和16.4%，而含有0.5%（质量分数）Mn元素的合金具有更高的抗拉伸强度，达到了1079 MPa，同时延伸率达到了15.8%。结论表明，强度的提高可以归因于Mn元素的固溶强化效应，同时Mn微合金化处理使合金中的Al元素富集于α相，有利于提高合金的强度和塑性。

Abstract:

The effects of Mn microalloying on the microstructure and mechanical properties of new near-α Ti-Al-Mo-Zr-Fe-B alloy were studied by OM, EBSD, and TEM. Results indicate that the addition of 0.5wt% Mn can refine the casting microstructure of the alloy from 3.28 μm to 2.65 μm, which leads to the increase in ultimate tensile strength from 882 MPa to 966 MPa. However, the elongation decreases from 7.8% to 5.1%. After forging, the grain size of two alloys tends to be similar, and the microstructure is more equiaxed. Besides, the microstructure becomes more homogeneous after Mn microalloying. The ultimate tensile strength and elongation of Ti-Al-Mo-Zr-Fe-B alloy increase to 966 MPa and 16.4%, respectively, whereas the alloy containing 0.5wt% Mn element possesses higher ultimate tensile strength, reaching 1079 MPa. Meanwhile, the elongation reaches 15.8%. These results suggest that the increase in strength can be attributed to the solid solution strengthening effect of Mn element. Additionally, the Mn microalloying promotes the enrichment of Al element in alloy into the α phase, which is beneficial to improve the strength and plasticity of the alloy.