更改表ALTER列是否中断正在进行的数据库访问?

I have a column in a table so that it is no longer NVARCHAR(256) but is NVARCHAR(MAX). I know the command to do this (ALTER TABLE ALTER COLUMN NVARCHAR(MAX)). My quesiton is really about disruption. I have to do this on a production environment and I was wondering if while I carry this out on the live environment there is a chance that there may be some disruption to usage to users. Will users who are using the database at the time be booted off? Will this operation likely take too long?I have a column in a table so that it is no lon