Duhamel, from Lively, Ont., and Radford, from Balmertown, Ont., scored 72.21 points to qualify for tomorrow's free program.
Russia's Tatiana Volosozhar and Maxim Trankov finished first with 84.17 points, well ahead of Germany's Aliona Savchenko and Robin Szolkowy with 79.64 points.
Kirsten Moore-Towers of St. Catharines, Ont., and Dylan Moscovitch of Toronto capped the program with 70.92 points to finish sixth.
Paige Lawrence of Kennedy, Sask., and Rudi Swiegers of Kipling, Sask. scored 58.97 to finish 13th.
The top 16 of the 20 pairs qualified for the free program.
Duhamel and Radford, bronze medallist at the 2013 world championships, skated to "Tribute," a piece of music Radford wrote in 2006 after the death of his coach Paul Wirtz. Radford is a pianist who studied at Toronto's Royal Conservatory of Music.
Canada claimed its first figure skating medal in Sochi on Sunday in the new team event.