The hypothesis that {TAIL ~ the retention} of Al and O at grain boundaries and {HEAD ~ triple points} would result in high fracture toughness was not correct 
The hypothesis that { TAIL ~ the retention } of Al and O at grain boundaries and { HEAD ~ triple points } would result in high fracture toughness was not correct
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH