研究了一种快速凝固粉末冶金高温钛合金的微观组织及其影响因素. 结果表明: 热等静压 (HIP)成形温度可以显著地改变钛合金粉末的显微组织, 当HIP成形温度为700 ℃时, 粉末中的α'马氏体相开始微量分解,900 ℃时大量分解, 分解产物为等轴/板条α相和晶界β相. α+β两相区HIP成形后的显微组织主要由等轴α相、板条α相和β相组成, 随着温度升高, 等轴相略有长大, 板条α相的长宽比显著降低; β单相区HIP成形后的显微组织为片层组织, 主要由粗大的片层α相和沿原始β晶界分布的晶间α相组成. 粉末粒度越小, HIP成形后的显微组织越细小. α+β两相区HIP成形并在α+β两相区进行热处理后的显微组织主要是由等轴α相和β转变组织组成的双态组织; β单相区HIP成形并在α+β两相区进行热处理后的显微组织是由等轴α相、板条α相和β转变组织组成的三态组织; α+β两相区或者β单相区HIP成形并在β单相区进行热处理后的显微组织均为较细的网篮组织. 稀土Nd含量增加, 显微组织的组成没有发生变化, 但基体中弥散析出的稀土相数量增加, 原始β晶粒尺寸明显减小.

The high temperature titanium alloy with rare earth element Nd addition was prepared by rapidly solidified powder metallurgy (RS－PM) processing. The microstructure of RS－PM high temperature titanium alloy has been investigated systemically. Microstructure study showed that the α' martensite phase in the RS powders initially decomposed at 700 ℃ and vastly at 900 ℃during the hot isostatic pressing (HIP) process. The decomposition products were equiaxed or lamellar α phase as well as grain boundary β phase. The microstructure of the specimen HIPed at the temperature in (α+β) phase field contained equiaxed α phase, lamellar α phase and β phase. The size of equiaxed α phase increased while the aspect ratio of the lamellar α phase decreased when the HIP temperature increased. The microstructure of the specimen HIPed at the temperature in β phase field contained coarsed lamellar α phase, grain boundary α phase and β phase. The microstructure became finer with decreasing the powder particle size. The microstructure of the sample HIPed in the (α+β) phase field and then heat treated in the (α+β) phase field was bi－modal microstructure containing equiaxed α phase and β transformed structure. The microstructure of the sample HIPed in the β phase field and then heat treated in the (α+β) phase field was ternary microstructure containing equiaxed α phase, lamellar α phase and β transformed structure. The microstructure of the sample HIPed in the (α+β) phase field or β phase field and then heat treated in the β phase field was basket－weave structure. The proportion of rich－Nd phases increased with increasing the Nd content,resulting in the reduction of original β grain size.