To understand the microstructure of any alloy system it is necessary to outline the phase relationships and constitution of the system being studied.
Titanium can exist in two crystal forms.
This temperature is known as the beta transus temperature. As alloying elements are added to pure titanium, the elements tend to change the temperature at which the phase transformation occurs and the amount of each phase present. Alloy additions to titanium, except tin and zirconium, tend to stabilize either the alpha or the beta phase. Elements called alpha stabilizers stabilize the alpha phase to higher temperatures and beta stabilizers stabilize the beta phase to lower temperatures.