By the dispersion of nanoscale quasicrystalline (Q) particles in f.c.c.-Al
or Zr-based glassy phase, new Al- and Zr-based alloys with good mechanical
properties were developed in a high Al content range of 93-95 at.% of Al-Cr
(or Mn)-Co-Ce, Al-Mn-Co-Cu and Al-Cr-Fe-Ti systems and in Zr65Al7.5Ni10Cu17
.5-xMx (M = Ag or Pd; x = 5 and 10 at.%) systems. The structure consists of
Q-particles with a size of 30-50 nm surrounded by Al with a thickness of 5
-10 nm for the Al-based alloys and Q-particles with a size of about 30 nm s
urrounded by glassy phase with a thickness of less than 1 nm for the Zr-bas
ed alloys. The Q-phase has high volume fractions (V-f) of 60-70% for the fo
rmer alloys and 80-90% fur the latter alloys. The former structure is forme
d by the solidification mode in which the Q-phase precipitates as a primary
phase, followed by precipitation of Al from the remaining liquid. The latt
er structure results from homogeneous nucleation and slow growth from the g
lassy phase. The high V-f of the Q-particles is presumably due to the exist
ence of randomly oriented icosahedral clusters in the supercooled liquid of
the Al- and Zr-based alloys. The features of mechanical properties are cla
ssified into four types, i.e., high-strength type of 800 MPa in Al-(Mn, Cr)
-Ce-Co systems, high elongation type of 30% in Al-Mn-Co-Cu system, high-ele
vated temperature strength type of 350 MPa at 573 K in Al-Fe-Cr-Ti system,
and high-strength type of 1900 MPa in the Zr-based system. These mechanical
properties are promising for the future extension of the new Al- and Zr ba
sed alloys to practical materials. (C) 2000 Published by Elsevier Science B
.V.