William & Mary hit a season-high 14 3-pointers on just 28 attempts.
Burchfield and Greg Malinowski hit back-to-back 3s to cap a 10-0 run to lead 43-41 with under a minute left in the first half.
Burchfield hit four straight 3-pointers during a 12-6 spurt for a 65-51 lead and William & Mary cruised.
Daniel Dixon added three 3-pointers, 18 points and six assists for William & Mary (13-5, 5-2 Colonial Athletic Association), which had 27 assists on 36 made field goals.
Sean Sheldon had a team-high nine boards as William & Mary outrebounded Elon 40-26.