The word Alfiyyah (أَلْفِیَّة, with a fatha and shadda on the ی) is derived from ألف, meaning "a thousand". The word Alfiyyah also refers to a collection of one thousand verses composed on a particular subject or discipline. Given this meaning, it is not appropriate to use this as a name.
As for Alfiyah (اَلْفِیَہ, with a fatha on the ی and without the shadda), this spelling was not found in any dictionary despite searching. Therefore, instead of this name, one should choose a name from the blessed names of the Ummahaat ul-Mumineen or the Sahabiyat, may Allah be pleased with them all.
Allah the Almighty knows best.
Darul Ifta Al-Ikhlas, Karachi.