钛硅黄铜中Si含量对凝固组织及力学性能的影响

Solidification Microstructure and Mechanical Properties of Titanium-Silicon Brass with Different Si Contents

通过熔体反应法制备了不同Si含量的钛硅黄铜,采用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对钛硅黄铜中硬质相的物相组成及三维形貌演变规律进行表征,分析Si含量对钛硅黄铜凝固组织的影响,并结合硬度及拉伸性能检测研究钛硅黄铜中微观组织与力学性能之间的关联性机制。结果表明,随着Si含量的增加,钛硅黄铜中合成硬质相的种类由片状枝晶状Al Cu_(2)Ti与六棱柱状Ti_(5)Si_(3)向多面体状Ti_(5)Si_(4)演变,硬质相的体积分数呈现先增加后趋于稳定的趋势;当Si添加量为1.5%(质量分数)时,大量未反应的Si元素促进了γ相基体的出现,合金基体由单一β相转变为β+γ相。Si含量在0.25%~1.5%(质量分数)变化时,钛硅黄铜的抗拉强度和硬度均随着Si含量的增加而持续增加,断后伸长率呈现先升高后降低的趋势,研究认为γ相的出现是合金断后延伸率下降的主要原因;在Si含量为1.0%(质量分数)时,钛硅黄铜的强塑性出现最佳配合,抗拉强度为(551±21) MPa,屈服强度为(276±16) MPa,断后伸长率为6.8%±0.3%。

In this paper,titanium-silicon brass with different Si contents was prepared by the melt reaction method.X-ray diffractometer(XRD)and scanning electron microscope(SEM)were used to characterize the evolution of three-dimensional morphology and phase composition of the hard phase,and analyzed the effect of Si content on the solidification structure of titanium-silicon brass.The relation-ship between the microstructure and mechanical properties of titanium silicon brass was investigated in combination with hardness and tensile property testing.The results showed that with the increase of Si content,the synthesized hard phase transformed from lamellar dendritic AlCu_(2)Ti phase and hexagonal prism Ti_(5)Si_(3) phase to polyhedral Ti_(5)Si_(4) phase,and the volume fraction of the hard phase showed a trend of increasing first and then stabilizing.When the Si content is added to 1.5%(mass fraction),a large amount of unreacted Si ele-ment promotes the formation ofγphase matrix,and the alloy matrix transforms from a singleβphase to aβ+γphase.When the Si con-tent changed from 0.25%to 1.5%,the tensile strength and hardness of titanium-silicon brass continued to increase with the increase of Si content,and the elongation after fracture showed a trend of first increasing and then decreasing,which is attributed to the formation ofγphase.When the Si content was 1.0%,the best combination of strong plasticity of titanium-silicon brass was presented,the tensile strength,yield strength and elongation after fracture were(551±21)MPa,(276±16)MPa and 6.8%±0.3%,respectively.