Austenite is a kind of metallurgical gentrification that happens when large numbers of nickel families invade a predominantly ferrite neighbourhood. At a critical population level they all say "we're not having this living arrangement anymore" and they start pushing the old iron residents around. They are powerful and it doesn't take many to cause a major transformation. The street grid is no longer square and the buildings start tilting. The cost of housing skyrockets.
Other visitors like the chromiums are much better behaved - they blend in, unlike nickel are happy to dance with others, and they even shield the hood from bad outside influences.
Hope that answers your question.
"Everyone is entitled to their own opinions, but they are not entitled to their own facts."