FIXATION OF HYDROGEN BY RARE EARTH IN Al-Si ALLOY

Occurrence of RE hydride was identified in the Al-Si alloy containing RE and enrichment of hydrogen in polynary RE intermetallic compound was determined by means of EPMA, secondary ion mass spectrography, Hg-free vacuum drivepipe hydrogen-meter to- gether with metallography and porosity measurement. The relative contents of various forms of hydrogen before and after RE added in Al-Si alloy have been qualitatively analysed. A concept about firm fixation of hydrogen by RE was suggested. It is believed that the hydrogen fixation is the major cause of reducing free hydrogen content and decreasing hydrogen-in- duced defects.