Boron and {HEAD ~ carbon} may be used as {TAIL ~ traditional sintering aids}, with nitrogen to suppress grain growth, and additions of yttrium and lanthanide elements to promote intergranular fracture 
used as
Boron and { HEAD ~ carbon } may be used as { TAIL ~ traditional sintering aids } , with nitrogen to suppress grain growth , and additions of yttrium and lanthanide elements to promote intergranular fracture
OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH