International Journal of Hydrogen Energy 32 (2007) 3936 – 3940. In this paper there is information on SFE changes. But the references listed in the paper such as 14, 15 etc. may lead you to find values of SFE.
I am sorry to note that Dr. ElRakayby. I found one more paper where you may find SFE if Ti-Al alloy. You may have to use that as the basis for estimating the SFE of Ti-4AL-4V alloy. .The reference is:http://www.sciencedirect.com/science/article/pii/S1359646206001667