, Riley Meredith and Josh Philippe were included, but there was no room for veterans Shaun Marsh and Nathan Coulter-Nile, who both featured in last year's World Cup.
Middle-order batsman Peter Handscomb was also overlooked while paceman Jhye Richardson is still recovering from shoulder surgery.
But superstar Maxwell returns after taking a break in October to deal with mental health issues.
Test discard Khawaja, who has not played for his country since being axed during last year's Ashes series in England, also gets a recall, as does all-rounder Marcus Stoinis.
"This preliminary list covers the contingencies of playing one-day internationals and T20 international in bio-secure hubs with the likely prospect of not being able to bring in replacements should the tour proceed," said selector Trevor Hohns.
"The preliminary list includes several exciting young players who have recently excelled at state level and in the Big Bash League.
"These emerging players are among those we would like to develop further as we believe they have a bright future in Australian cricket."
Australia preliminary squad: Sean Abbott, Ashton Agar, Alex Carey, Pat Cummins, Aaron Finch,Josh Hazlewood, Travis Head, Usman Khawaja, Marnus Labuschagne, Nathan Lyon, Mitchell Marsh, Glenn Maxwell, Ben McDermott, Riley Meredith, Michael Neser, Josh Philippe, Daniel Sams, D'Arcy Short, Kane Richardson, Steve Smith, Mitchell Starc, Marcus Stoinis, Andrew Tye, Matthew Wade, David Warner, Adam Zampa.