I did not find a Nif'al version of this root (ח - ל - ף) in Pealim, only a Pa'al https://www.pealim.com/dict/607-lachalof/ and a Hitpa'el https://www.pealim.com/dict/609-lehitchalef/. But I am not a native speaker, so I need somebody who is or who is more experienced in Hebrew to confirm it. If there were a Nif'al verb of this root, it would be written נחלף nichlaf? for 3. person sing. masc. in the present and the past with the infinitive להיחלף? But nothing like it is on Pealim.