When Al contents increased above {TAIL ~ about 2 wt %}, it was necessary to heat rapidly in order to achieve {HEAD ~ high density} 
When Al contents increased above { TAIL ~ about 2 wt % } , it was necessary to heat rapidly in order to achieve { HEAD ~ high density }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD