HIGH-PRESSURE AND HIGH-TEMPERATURE INVESTIGATIONS ON INTERMETALLIC COMPOUNDS USING ENERGY-DISPERSIVE X-RAY-POWDER DIFFRACTION

The intermetallic compounds Mg2Si, MoSi2, WSi2, CrSi2, NbSi2, Ti5Si3, TiSi2, ZrSi2 and Al3Nb were investigated in a pressure range up to 70 kbar and a temperature range up to 1500 degrees C in order to determin e previously unknown elastic constants and possible phase transformati ons. The experiments were carried out using the multi-anvil-X-ray appa ratus MAX-80 and synchrotron radiation at HASYLAB. A complete phase tr ansititon of cubic Mg2Si to a hexagonal phase was observed at 70 kbar and 450 degrees C. The high-pressure/high-temperature phase was quench ed and recovered for further investigations. All the other compounds r emained stable in the mentioned pressure and temperature range. The bu lk moduli covered the range from 436 (10) (Mg2Si) to 3350 (190) (WSi2) kbar.