If material certification is your intent, then converting Vickers microindentation hardness to macro scales will not be valid and should not be attempted. If you must do so and there is no conversion scale available (have you checked ASTM E140?), I would establish a comparison by measuring with both scales on a single product of the same material and that has been processed in the same way as the part you ultimately want to measure. This approach could be valid for quality control purposes. A certified hardness block of hardness in the same range could serve this purpose (but they don't tend to produce them from nickel).
"Everyone is entitled to their own opinions, but they are not entitled to their own facts."
You would need to develop your own correlation using samples of various hardness levels.
If the Ni alloy is age hardenable then this will not work. The micro hardness will be greatly effected if the indentor hits a precipitate, where as macro tests will give you and average.
I you need small indention a superficial Rockwell may the best that you can do. Even then you will need your own conversion and you won't be able to certify it.
I've checked ASTM E140 and spec. allows me to convert from 1kgf,5kgf,10kgf,30 kgf vickers to rockwell c for nickel alloys.So, i am going to develop my own correlation table from heat treated raw material block.
