Biomaterials - Bionanomaterials for Dental Applications - page 47

structures that are developed under different thermomechanical
processing conditions are shown in Fig. 3.4 [46]. The alloys
processed/heat treated above the β transus temperature result in
acicular or lamellar structure and are typically known as β treated
structure. When these alloys are mechanically processed below the
β transus ( α + β phase ield) and heat treated in α + β phase region,
the microstructure consists of a mixture of equiaxed α and β phases.
Depending upon the alloy chemistry, heat treatment temperatures,
and cooling rate, volume fraction of equiaxed α and nature of β
phases may change. In faster cooled structure, transformed β phase
may constitute martensite or α laths along with the retained β ,
while on slow cooling the transformed β phase may entirely be
retained β . In metastable β alloys, the β phase is usually retained
on quenching from the β phase ield and very ines a precipitates on
aging at lower temperatures, which leads to extremely high strength
in these alloys [46].
Figure 3 . 4 Inluence of thermomechanical processing on development of
various microstructure in alpha beta titanium alloys [46].