Is saying "Allah Hafiz" allowed when we are leaving? In Pakistan, it is very common practice, and if some one says al-Salamu Alaikum when we are leaving, it is considered awkward. So I want to know if it is allowed to say "Allah Hafiz" instead of al-Salamu Alaikum?

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

If they replace the expression "Allah Hafiz" with "al-Salamu Alaikum" then this practice is contrary to Sunnah. If they use this expression after saying "al-Salamu alaikum" then it is permissible because it is a kind of supplication that may Allah protect one and doing so is permitted in Sharia.
Allah knows best.