The youngsters will spend the rest of the Australian A-League season at Central Coast Mariners, under the guidance of former United midfielder Nick Montgomery who is the Mariners’ assistant manager.
"It will be an excellent and challenging experience for both lads,” Binnion, himself a former Blades trainee, said.
“The A League is a strong league and will provide numerous learning opportunities for them to further their development."
Graham spent the first half of this season on loan at Oldham, while Mallon recently recovered from a serious injury.