Titanium-Chromium embrittlement

[andyfox1]

Hi all,

Does anybody know of any potential embrittlement issues of a chromium-titanium interface undergoing 2-3 hours heating at a temperature of about 450-550C? One of my colleagues mentioned offhand that he was told this can bring about a reduction in fatigue life of compressor blades undergoing HCF testing but hasn't provided me with any references, and my knowledge of materials is sketchy at best!

I've done a good few hours of online searches, and my access to proper articles or books is limited; I have had no luck in finding an answer.

Can anyone suggest any articles or books that have this information, or explain why such a reduction may occur?

Much appreciated,

Andy

 

[EdStainless]

Have you looked at a phase diagram and diffusion coef?
That is where I would start.
Look for references to the formation of Ti intermetallic compounds.

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Plymouth Tube

 

[TVP]

Can you please explain the materials/coatings in a little more detail? Are you saying that the compressor blade is fabricated from a titanium alloy and that there is some type of chromium-based coating on top of it? Hard industrial chromium? HVOF spray with chromium? Something else? Environment? Chemical species present?

 

[metengr]

There are various patents dealing with Ti-containing alloys and deposition of coatings on these alloys. Some of the patents like the one below may be useful to review for starters;

http://www.patentstorm.us/patents/5783315/fulltext.html

 

[andyfox1]

EdStainless - a-ha, the diffusion coefficient coupled with phase diagrams! I've started digging in those directions...

TVP - it is essentially a thin (~0.3-0.4 micron) Cr-interlayer on a Ti-alloy prior to the gradual phase-in of different metals through a PVD process. We've never experienced any problems with Ti-substrates before tto be honest but I'd like to cover all bases.

metengr - that link proved to be very useful. I think I'll have to have a good look at the patent sie of things to make sure I'm not crossing over anybody else's proven processes.

Many thanks for taking the time out to answer my post.

Andy