氧含量对激光定向能量沉积Ti-6Al-4V钛合金组织和性能的影响

Effects of Oxygen Content on Microstructure and Mechanical Propertiesof TC4 Titanium Alloy Deposited by Laser Directional Energy Deposition

采用激光能量沉积法制备了TC4钛合金试样块,借助OM、SEM、电子探针定量分析、X射线衍射等方法,研究了不同氧含量对钛合金微观结构、相组成、氧气浓度及性能之间的相关性。结果表明,衍射峰的强度随着氧含量的增加而略有增加。而(002)衍射峰的强度明显在中氧环境下达到最大,随之减弱。材料的强度和硬度随着氧含量的增加分别提高115 MPa和58 HV,伸长率下降到8.71%,断面收缩率下降到6.6%。断裂失效机制随着氧含量的增加由韧性断裂转变为准解理与韧性断裂复合断裂。宏观组织主要为柱状晶粒和针状马氏体为主,热处理后主要是马氏体α'和β转组织。不同氧含量环境下形成的间隙固溶体,导致晶格常数增大,从将引起晶格膨胀。随着界面能量的增加,进而在晶界生成高密度位错现象,对钉扎起到进一步加强作用,使试样强度提高而塑性降低。

TC4 titanium alloy samples were prepared by laser energy deposition.The correlation of different oxygen content on the microstructure,phase composition,oxygen concentration and properties of titanium alloy was studied with OM,SEM,electron probe quantitative analysis,X-ray diffraction and so on.The results show that the intensity of the diffraction peak increases slightly with the increase of oxygen content.The intensity of the(002)diffraction peak obviously reaches the maximum in the medium oxygen environment,and then weakens.With the increase of oxygen content,the strength and hardness of the material increase 115 MPa and 58 HV respectively,the elongation decreases to 8.71%,and the section shrinkage decreases to 6.6%.The fracture failure mechanism changes from ductile fracture to compound fracture of quasi-cleavage and ductile fracture with the increase of oxygen content.The macrostructure is mainly columnar grain and acicular martensite,and the transformation structure of martensite isα'andβT after heat treatment.The interstitial solid solution is formed in different oxygen content environment,which leads to the increase of lattice constant,then leads to lattice expansion.With the increase of the interface energy,the high density dislocation phenomenon is formed at the grain boundary,which further strengthens the pinning and increases the strength,but decreases the plasticity of the sample.