The present invention relates to the manufacture of fully dense strips, plates, sheets, and foils of
titanium alloys,
titanium metal matrix composites,
titanium aluminides, and flat multilayer composites of said materials manufactured by direct rolling and
sintering of blended powders. The resulting
titanium alloy flat products are suitable in the
aerospace, automotive, sporting goods, and other industries. The process includes the following steps: (a) providing a C.P. titanium matrix
powder and at least one
powder of alloying components such as elemental alloying
powder, pre-alloyed master
alloy powders, and / or hard reinforcing particles, (b) mechanical activation by attrition of all alloying components, whereby the particle size of attrited alloying powders is at least ten times smaller than the particle size of the matrix
titanium powder, (c) blending
titanium powder as a ductile matrix material with attrited alloying powders obtained in step (b), (d) cold direct powder rolling of the blend in a mill with horizontally-positioned rolls to achieve density of the rolled strip of 60±20% of the theoretical value, whereby diameters of rolls are different, so that the green strip is bent for the subsequent densification by a second horizontal re-
rolling mill staying in line with the first powder
rolling mill, and rotations of edging pair of rolls of at least one of the said mills differ in the rate by 5-15% to promote densification of the green strip by shear deformation, the
diameter of the rolls of the direct powder
rolling mill is 40-250 times larger than thickness of the rolled strip, (e) densification by cold re-rolling of the green strip in a horizontal rolling mill, whereby
diameter of the rolls of the densification mill is 1.1-5 times larger than the
diameter of rolls of the direct powder rolling mill to provide compressive action and avoid shearing action of the green strip and achieve density of the rolled strip in the range of 90±10%, (f) multiple cold re-rolling of the strip in vertically-positioned rolls at equal rotation rate of the edging rolls to achieve density of the green rolled strip about 100% of the theoretical value, and (g)
sintering of near fully-dense green rolled strip in vacuum, or in protective
atmosphere batch furnace, or in continuous belt furnace in protective
atmosphere. Typical mechanical properties of fully-dense Ti-6Al-4V
alloy strips manufactured by the process of the present invention are: tensile strength is 130-140 ksi (897-966 MPa), yield strength is 120-130 ksi (828-897 MPa), and elongation is over 10%.