Goalkeeper Langfield has joined forwards Maguire and Aluko in being offered a new deal, but midfielder Derek Young, defender David McNamee and goalkeeper Mark Howard have been informed they will be free to leave.
Brown paid tribute to Young on the club's official website: "Derek's commitment and willingness to play in a variety of positions for the team made him an invaluable asset for us this season and it was a very hard decision for us to make but by allowing Derek to leave it will enable us to free up space to recruit new players."
He added: "It is in no way a reflection of his efforts for the club, which have been exemplary.
"Mark Howard understandably wants to play every week and he was clearly number two here so he will now get the opportunity to play elsewhere.
"David McNamee has been bedevilled by injury during his time here but he made a great contribution to the team short term when we were struggling at full-back."
On-loan Nikola Vujadinovic and Nick Blackman will return to Udinese and Blackburn, respectively, while Myles Anderson will join Rovers at the end of the current campaign.
Steven Smith is set to return to parent club Norwich, but Aberdeen manager Craig Brown hopes to re-sign the defender.
Zander Diamond is also out of contract at the end of the current campaign and Brown has previously admitted he expects the defender to depart, with Hearts a possible destination.
Source: PA
Source: PA