No. The intellect of an angel is not in potentiality because an angel's intellect is never in potentiality with regard to the things to which his natural knowledge extends.
But with regard to things divinely revealed to them, there is nothing to hinder them from being in potentiality.
An angel's intellect can be in potentiality with regard to things learnt by natural knowledge; for he is not always actually considering everything that he knows by natural knowledge.
But as to the knowledge of the Word, and of the things he beholds in the Word, he is never in this way in potentiality; because he is always actually beholding the Word, and the things he sees in the Word. For the bliss of the angels consists in such vision; and beatitude does not consist in habit, but in act, as the Philosopher says (Ethic. i, 8).