TC4钛合金负压真空脉冲渗氮层的组织与性能

Microstructure and properties of negative pressure pulse vacuum nitriding layer of TC4 titanium alloy

在氮气为负压及不同温度条件下(750、800、850和900℃)对TC4钛合金进行真空脉冲渗氮处理,采用X射线衍射,自动显微硬度测试、滑动干摩擦及电化学极化试验等手段分析了渗氮硬化层的组织与性能。结果表明:TC4钛合金渗氮处理后表面形成了一层由TiN_(0.3)、TiN、Ti_2N和AlTi_2N组成的多相化合物层;其表面硬度、渗层深度及耐磨性均随渗氮温度升高而提高。其中,850℃渗氮后合金有效硬化层深度约为30μm,硬度梯度平缓,其磨损量比原样下降1个数量级,综合性能最优。真空渗氮后合金耐蚀性均能得到大幅度改善。

Under negative pressure and different temperatures（ 750,800,850 and 900 ℃）,vacuum pulse nitriding treatment of TC4 titanium alloy was carried out.Microstructure and properties of the nitriding hardening layer were analysed by X-ray diffraction（ XRD）,microhardness test,dry sliding friction and automatically electrochemical polarization test.The results show that the surface of the TC4 titanium alloys after nitriding treatment forms a multiphase compound layer composed of TiN_（0.3）,TiN,Ti_2N and AlTi_2N.The surface microhardness,penetration depth and wear resistance of the layer increase with the increasing of nitriding temperatures.The optimum performance of the alloy is obtained when nitriding at 850 ℃,which the effective hardening layer depth of the alloy is about 30 μm,and it has the most gentle hardness gradient and the wear loss is lower by more than one order of magnitude.After vacuum nitriding,corrosion resistance of the samples is greatly improved.