$Al_3M(M=Ti,Zr)$ intermetallic compound was modified by substituting transition elements in order to design a dispersion phase having high coarsening resistance in Al alloys for high temperature application. The addition of 4-period transition element to the tetragonal $Al_3(TiZr)$ phase produces the cubic $Ll_2$ type $Al_{3-x}M_x(Ti,Zr)$ and this $Ll_2$ structure has better interface matching property with Al-matrix than $D0_{23}$.
IDS(intermetallic dispersion strengthened) alloying method has a lot of advantage such as control the portion of IMC and restraint for the formation of undesired phase etc. Pressure is not major factor for phase stability in VHP process, but just for condensation. About 300MPa is best condition without damaging facilities. Most of all VHP temperature is decisive factor because phase transformation more dependent on the temperature. Phase transformation of dispersed IMC occurs during heat treatment (450℃) because $Ll_2$ structure is not stable in high temperature and 4-period elements (Mn, Cr, Cu etc) dissolved into the Al-matrix. At room temperature $D0_{23}-IDS$ alloys has higher compress strengths than $Ll_2-IDS$ alloys. But $Ll_2-IDS$ alloys are more ductile and better in strength as well as ductility at high temperature.
