等离子旋转电极雾化法制备高品质Ti-6.5Al-1.4Si-2Zr-0.5Mo-2Sn合金粉末

摘要

This research aims to prepare high quality powder of Ti-6.5Al-1.4Si-2Zr-0.5Mo-2Sn,which lays foundation for the following preparation of powder high temperature titanium alloy component. Ti-6.5Al-1.4Si-2Zr-0.5Mo-2Sn alloy ingots were prepared by vacuum arc remelting (VAR).The chemical compositions of ingots were examined.The loss of alloy elements,uniformity of composi-tion,phase composition and microstructure of titanium alloy ingots were analyzed.Then powders were prepared by plasma rotating electrode process (PREP)with different rotating speeds.Alloy powders were sieved into different particle sizes.The relationship between rotating speed and physical and chemical properties of powder was studied.X-ray diffraction(XRD),scanning electron microscope (SEM)and metallurgical microscope(OM)were used to investigate the phase composition,morpholo-gy and microstructure of the powder.The results show that the composition distribution of titanium alloy ingot prepared by VAR is uniform and the content of alloy elements meets the requirements of national standard,through a unique pressing electrode.Microstructure of the ingot is lamellar struc-ture with small amounts of silicide particles disperse in the matrix.The size distribution of the pow-ders made by PREP method exhibits the normal distribution.The sphericity of the powder is excel-lent,and no hollow ball and satellite ball exists.With the increase of rotating speed,the proportion of small particles increases dramatically,the proportion of large particles decreases greatly.The phase composition of powder is mainly α′phase,and it is mainly composed of peritectic and small amount of dendrite structures.Compared with the alloy ingot,the elements of the powders have a slight loss, the content of O is less than 0.1%,which is beneficial to obtain high-performance powder titanium alloy.%旨在制备高品质Ti-6.5Al-1.4Si-2Zr-0.5Mo-2Sn粉末,为后续粉末高温钛合金构件的制备奠定基础.首先采用真空自耗电弧熔炼(VAR)技术制备Ti-6.5Al-1.4Si-2Zr-0.5Mo-2Sn合金铸锭,对铸锭进行化学成分检测,并分析其合金元素损耗、成分均匀性以及显微组织和物相组成.利用制得棒料,采用等离子旋转电极雾化法(PREP),选取不同转速制备得到钛合金粉末,将粉末筛分成不同粒度范围.研究了棒料转速与粉末理化性能间的关系.采用X射线衍射分析仪(XRD)、扫描电镜(SEM)、金相显微镜(OM)分别分析了粉末的物相组成、形貌和微观组织.研究表明:通过独特的压制电极设计,可制得成分均匀、元素损耗小的钛合金铸锭,且各合金元素含量满足国标的要求.铸锭微观组织为层片状结构,基体中存在少量大小不均的Ti5 Si3硅化物相.PREP法制得的钛合金粉末呈正态分布,且球形度好,无空心球和卫星球.随着转速增加,小颗粒粉末占比增加,大颗粒粉末占比大幅度降低.粉末颗粒以胞状组织为主,存在少量的枝晶.合金粉末主要由α′马氏体相组成.相比合金铸锭,粉末中各合金元素略有损耗,O元素质量分数小于0.1%,有利于制得高性能的粉末钛合金.