A Novel Surface Treatment Technique for Titanium Alloys
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https://doi.org/10.1007/s11837-020-04393-0 Ó 2020 The Minerals, Metals & Materials Society
SURFACE ENGINEERING: APPLICATIONS FOR ADVANCED MANUFACTURING
A Novel Surface Treatment Technique for Titanium Alloys MING-XING ZHANG
,1,3 SHOU-MOU MIAO,1 and YI-NONG SHI2
1.—School of Mechanical and Mining Engineering, The University of Queensland, St Lucia, QLD 4072, Australia. 2.—Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, People’s Republic of China. 3.—e-mail: [email protected]
A novel packed-powder diffusion coating (PPDC) technique for pure Ti and Ti alloys was developed to improve their oxidization resistance and wear resistance. The treatment led to the formation of a controllable Al3Ti intermetallicbased composite coating, of which the thickness varied from 100 lm to 1295 lm depending on the treatment temperature and time. Cyclic oxidization tests in a static air within the temperature range from 800°C to 1000°C for 24 cycles indicated that the PPDC treatment significantly increased the oxidization resistance of Ti alloys, which enabled this type of light alloy to be comparable with some Ni-based superalloys. Furthermore, the PPDC-treated Ti alloys also showed a reduced friction coefficient and increased wear resistance compared with the substrates. Hence, it is reasonable to consider that, after the PPDC treatment, the lightweight Ti alloys had strong potential to partially replace Ni-based superalloys for high-temperature applications.
INTRODUCTION The lightness, high strength and excellent corrosion resistance are major advantages of titanium (Ti) alloys, which are attracting increasing interest in wider industrial applications, the aerospace industry in particular.1 However, Ti alloys also suffer from poor oxidization resistance when they serve in high-temperature environments because of the high affinity of Ti to oxygen and from low wear resistance when they are used as abrasively stressed parts. This not only shortens the service life but also limits their wider applications in areas associated with high temperature and heavy wear. For example, the most typical Ti6Al4V alloy can only be used up to 300°C. Even for the Ti1100 and IMI834 alloys, which are designed for high-temperature applications, their application temperature is < 600°C.2,3 In addition, the current issue associated with carbon emissions drives the transportation industries to increase fuel efficiency to decrease fuel consumption. To achieve this goal, one of the most effective approaches is to reduce the weight of vehicles. For the jet engine of an aircraft, the weight reduction in hot sections is especially (Received June 11, 2020; accepted September 16, 2020)
effective to increase the fuel efficiency. Hence, TiAl-based alloys have been developed to replace the Ni-based superalloys for low-pressure turbine blades.4 However, the major drawback of TiAl-based alloys is the low room temperature ductility.5 Compared with this intermetallic alloy, Ti alloy
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