TiH_2粉末制备钛合金的烧结脱氢规律及工艺

Dehydrogenation and Sintering Process of Titanium Hydride for Manufacture Titanium and Titanium Alloy

以TiH2粉末为原料,通过压制成型和烧结工艺制备粉末钛合金,不同于传统钛粉末冶金方法。通过热分析和热膨胀技术研究不同球磨粒度TiH2粉末的脱氢和收缩规律,以此入手研究了TiH2粉末压坯和TiH2-Al-V粉末压坯的烧结致密特性,以及影响烧结过程的主要工艺因素,包括烧结温度、烧结时间、升温速率、压坯密度、压坯成型方式、合金体系,并对烧结组织进行了分析。结果表明,TiH2粉末球磨后脱氢温度降低,粉末越细,开始温度越低。TiH2粉末压坯在烧结过程中脱氢后获得新鲜钛,其易发生黏接并引起α-Ti的强烈收缩,这时烧结体很容易致密,并获得相对密度大于99%坯体;相比之下,TiH2-Al-V粉末压坯烧结时因为合金元素的溶解,不如纯TiH2粉末压坯的烧结容易致密。TiH2-Al-V粉末经过成型、烧结脱氢可获得典型的层片状α+β钛合金组织,合金元素分布均匀。

Using the titanium hydride powder directly as the starting material to manufacture the titanium and titanium alloy is a method that goes beyond the traditional powder metallurgy technology.Dehydrogenation and shrinkage of TiH2 powders with different particle sizes are studied using thermogravimetric and dilatometric techniques.The process factors such as the sintering temperature,,the sintering time,the heating rate,,the compaction density,,the compaction methods,and the alloy system,would affect the sintering densification of TiH2 powders and TiH2-Al-V alloy powder.It is shown that the dehydrogenation temperature of the starting and ending of the ball milling TiH2 is lower than that of the coarse TiH2 powders,the finer the TiH2 powder,the lower the temperature.The densification of TiH2 powders is easy because of the combination of dehydrogenation and shrinkage of α-Ti in one process,which creates the fresh dehydrided titanium uniform during sintering,thus leads to rapid densification and very high sintereing relative density,higher than 99%.In contrast,it is difficult to achieve a full densification of TiH2-Al-V alloy powder during sintering,which requires dissolution of alloy elements during sintering above its beta transformation temperature.The sintered microstructure of Ti-6Al-4V shows the typical lamellar shaped α＋β characteristics,with a uniform alloy element distribution.