Compression testing of quasicrystalline materials

Abstract

Abstract Mechanical compression tests were applied to a few alloys, either truly quasicrystalline or made of approximant, crystalline phases with large unit cells. A1-Cu-Co-Si, A1-Cu-Fe-Cr-Si-(B) and A1-Cu-Fe-(B) alloys are brittle materials at low temperature but they show high plasticity at temperatures beyond 625-650°C. In A163Cu17·5Co1·7.5Si2, more than 30% of volumic porosity was found in the samples after compression testings at T > 700°C or after heating and cooling from T > 700°C with a rate 5°Cmin-1. The implication of pore formation in the high plastic behaviour is pointed out. For the A1-Cu-Fe-Cr-Si alloys, the prismatic single crystals show signs of anisotropic mechanical properties along the tenfold and twofold directions, respectively. Small amounts of boron addition modifies the structure of the A1-Cu-Fe-Cr-Si and A1-Cu-Fe alloys and markedly enhances the fracture strength of the materials. The structural modifications are discussed.