Effect of Fe addition on sintering behaviour of titanium powder

Abstract

property, subsequent thermomechanical treatments have to be used for sintered products, including hipping and hot The eVect of iron on the sintering behaviour of forging.4,5 titanium powder was investigated from two aspects:To make more eYcient use of these bene ts in the BE (1) diVusional homogenisation of iron; (2) densi cation process, some new titanium alloys were developed, including of Ti-5Fe alloy. Under the present process conditions Ti-5Al-2Cr-1Fe,6 Ti-6·8Mo-4·2Fe-1·4Al-1·4V (Ref . 7) and ( heating rate of 5 K minÕ 1 and iron content 5 wt-%),Ti-4·5Al-3V-2Fe-2Mo.8 In these titanium alloys, Fe was iron dissolved into the titanium matrix thoroughly added to substitute partially more expensive vanadium. before the rst eutectic temperature; potential liquid Majima et al.9 studied the eVect of diVerent iron content phase did not appear. The addition of iron enhances the on the sintered density, microstructure and tensile properties sinterability of titanium alloys because the mobility of of pure titanium powder. The eVect of iron on the microtitanium atoms is accelerated by the rapid diVusion structure and the mechanical properties of Ti-5Al-2Cr-1Fe of iron. Most sintering shrinkage is achieved during was investigated by Hagiwara et al.6 Fujita et al.10 reported the heating stage from 950 to 1250°C. Based on the that the addition of transition element Fe could achieve diVusion creep mechanism of Nabarro-Hering, the higher sintering density in Ti-4·5Al-3V-2Fe-2Mo using the result can be explained as a combination of the diVusion same sintering process as compared with Ti-6Al-4V. They coeYcient D and inherent local sintering stress s, found that addition of iron could achieve higher sinterability and the dissolution of iron in titanium is expected to and better strength-ductility balance for titanium alloys, reduce the creep strength of the Ti matrix at high and consequently eliminate costly hipping or hot forging temperatures due to its very fast diVusion rate. The techniques. However, successful veri cation of its eVect eVect of iron on the microstructure of Ti-5Fe alloy is on the sintering behaviour of blended elemental titanium also discussed. The formation of a Widmanstättenlike alloys has not been thoroughly analysed, and a reasonable microstructure in Ti-5Fe alloy can be attributed to a mechanism regarding this eVect has not been suggested. In b stabilising eVect and a high diVusion rate of iron the present article, compared with the sintering behaviour during furnace cooling.PM/1019 of pure titanium, the densi cation mechanism and microstructure evolution of Ti-Fe alloy (iron content=5 wt-%) EXPERIMENTALThe characteristics of raw powders used in the experiment are listed in Table 1. Hydride-dehydride pure titanium powder and pure iron powder were blended in an attritor INTRODUCTIONfor 30 min, followed by uniaxial die pressing to a relative Titanium alloys have various advantages over ferrous and density of 86% and sintering at 1250°C for 3 h in a vacuum non-ferrous materials, such as high strength to wei...

Microstructural Evolution during Pressureless Sintering of Blended Elemental Ti-Al-V-Fe Titanium Alloys from Fine Hydrogenated-Dehydrogenated Titanium Powder

“…The sinterability of titanium alloys can be enhanced by the addition of iron since the mobility of titanium atoms is accelerated by the rapid diffusion of iron [13,17,18]. The fast diffusion of iron in titanium alloy is evidenced by the fact that iron is essentially uniform in a blended elemental Ti-10V-2Fe-3Al alloy when heated at 5 • C/min to 1200 • C [19].…”

“…Current titanium powder metallurgy research has been largely devoted to cost reduction in titanium components by both developing cost-effective powder manufacturing and developing low-cost titanium alloys [10][11][12]. In the development of low-cost titanium alloys, the introduction of iron (Fe) as a β-Ti stabilizer into the alloy compositions has been widely explored for powder metallurgical titanium alloys [13,14].…”

Improvement of Ti Processing through Colloidal Techniques

“…In previous works, the authors have employed sintering temperatures ranging between 1250 and 1350 ºC, and times as long as 2 or 4 hours, to obtain densities of about 95% of theoretical [3,4,5]. As a consequence of the high temperature and prolonged times the grain size becomes coarse, the content of interstitial elements is high, and the final properties are lower than expected.…”

The Sintering, Sintered Microstructure and Mechanical Properties of Ti-Fe-Si Alloys

“…[7,8] From a PM standpoint, Fe is a fast diffuser in both a-Ti and b-Ti. [9] For example, Fe was found to be essentially uniform in a blended elemental Ti-10V-2Fe-3Al when heated at 5 K/min to just 1473 K (1200°C). [10] A faster diffuser may favor the self-diffusion of the base atoms [11] and enhance densification.…”

“…A range of PM Ti-Fe alloys has thus been assessed. [9,[12][13][14][15][16][17] Chen et al [12] sintered Ti-3Fe, Ti-5Fe, and Ti-7Fe (pct) blends made from low oxygen (0.134 pct) fine Ti powder (25 lm) and Fe (3.4 lm) powder. Excellent properties were obtained from each alloy, particularly the as-sintered Ti-7Fe, which attained tensile properties similar to wrought Ti-6Al-4V.…”