钛氮合金的铸态组织与性能

采用熔铸工艺法制备了含氮量为0.045%～0.27%的原位自生氮化物增强钛基复合材料,分析并测试了合金的铸态组织和力学性能.研究结果表明:在Ti-N合金中,随着氮含量的增加,合金中氮化物的形态和相组成发生了明显的改变;当氮含量在0.045%～0.18%时,合金的基体为α-Ti,增强相为TiN0.3;氮含量增加到0.225%时,增强相转变为块状Ti2N;复合材料的硬度、抗压强度和弹性模量均高于纯钛基体且随着氮含量的增加而增加;当增强相由TiN0.3转变为Ti2N时,抗压强度显著增加;由压缩断口分析可知,基体为韧性断裂,随着氮含量增加合金由韧窝 解理断口向具有解理特征的脆性断裂转变.

As-cast microstructure and mechanical properties of Ti-N alloys

In this paper, titanium matrix composites containing nitrides in which N content ranging from 0. 045wt% to 0. 27wt% were fabricated by using in-situ melting-casting process. The as-cast microstructure and mechanical properties of Ti - N alloys were studied. The results indicate that the morphologies and constitution of nitrides in Ti - N alloys vary significantly with the increasing of N content. When N content ranges from 0. 045wt% to 0. 18wt% , reinforcements in ct -Ti matrix are TIN0.3 phase which are fine dendrite and linearly distribute in matrix. In addition, a few thin plates precipitated along grain boundary. When N content increases to 0. 225wt% , reinforcements change into block-like Ti2N and distribute in grains and along grain boundaries. The hardness, compressive strength and elastic modulus of the Ti - N alloys are higher then those of matrices. Furthermore, with the increasing of N content, the hardness, compressive strength and elastic modulus of Ti - N alloys were further increased. When the reinforcement phase transforms from TIN0. 3 into Ti2N the compressive strength increases remarkably. On the base of analysis of fractographies, it shows that matrix fracture is ductile. With the increasing of N content, alloy fracture transforms into brittle fracture that has the characteristics of transgranular cleavage.