We tried to grow Al-Pd-Mn icosahedral quasicrystal (IQC) by floating zone melting technique. Molten block of Al73.2Pd19.3Mn7.0 at around 1140 K was travelled through a bar of Al69.4Pd20.3Mn10.3 at the rate of 1.1 to 14 μm/s. The sample obtained (about 1 cm in diameter and about 6 cm in length) was cut in several slices and some of them were annealed at 1073 K for 20 hr in evacuated state. The bulk composition of the sample was Al69.6Pd20.3Mn10.1 and almost unchanged along the growth direction. The largest grain was about 5 mm in diameter and several tens of mm along the growth direction. The sample was made mainly of IQC of Al69.8Pd21.4Mn8.8, and a small amount of decagonal quasicrystal (DQC) of Al68.6Pd13.3Mn18.1 was seen as fine exsolution lamellae and grain boundary phase. The electron diffraction pattern taken along the two-fold symmetry axis showed that our IQC is Fl type of Ishimasa and Mori (1992). Micro-Vickers hardness (HV) was about 950 at 25 g, irrespective of annealed or as-solidified and of the presence or absence of DQC lamellae. HV decreased with increasing load, as reported formerly. The fracture toughness (KIC) of annealed sample with lamellae (2.1 MPam1/2) was about 1.5 tunes as large as that of annealed one without lamellae (1.3 MPam1/2) and as-solidified one with lamellae (1.4 MPam1/2).
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