Ti-Al-B合金中铝含量对硼化物的存在方式和形态的影响

Influence of Al content on constitutes and morphologies of borides in Ti-Al-B alloys

用熔铸法制备了硼化物颗粒增强钛基复合材料 ,通过XRD和SEM ,详细研究了含铝量变化时合金的相组成及硼化物的形态和存在方式的变化规律 .结果表明 :合金的相组成主要受铝含量的影响 ,铝含量相对较低时合金基体为α -Ti,硼化物为单一的TiB ,铝量增加时基体中形成α2 相及γ相 ,并开始出现TiB2 ,合金中TiB含量逐步减少 ,TiB2 含量逐步增加 ,最终硼全部以TiB2 形式存在 ;硼化物形态上共晶TiB主要呈针状或片状 ,尺寸为 2 0～ 5 0 μm ,TiB量少时呈现沿晶界分布特征 ,硼量增加时开始出现板状TiB ,TiB2 典型形态为六面棱柱体块状 。

Boride particles reinforced titanium alloy matrix composites were prepared by using melting casting method. The phase constitutes and morphologies of borides varying with Al content were investigated by using XRD and SEM techniques. The results indicate that the phase constitutes of composites are influenced by Al content. At lower Al contents, the matrix is α-Ti, the boride is simply TiB. With increasing Al content, α 2 and γ phases are formed in the matrix and the TiB 2 phase appears instead of TiB. Finally, the total content of β appears in the form of TiB 2. The eutectic TiB particles are needle like or in the form of plates, with a size of 20～50 μm. TiB may have a grain boundary character of distribution when the amount of TiB is small. With increasing the B content, the lath like TiB appears and the typical form of TiB 2 is hexagonal prism with block shape or branches.