anneal vs vitrify

anneal

verb
  • To cool glass slowly, to minimize internal stress. 

  • To subject to great heat and then (often slow) cooling, and sometimes reheating and further cooling, for the purpose of rendering less brittle; to temper; to toughen. 

  • To make a double-stranded nucleic acid by pairing a single strand with a complementary strand. 

noun
  • An act of annealing. 

vitrify

verb
  • To be converted into glass, especially through heat. 

  • To convert into glass or a glass-like substance by heat and fusion. 

How often have the words anneal and vitrify occurred in a corpus of books? (source: Google Ngram Viewer )