The Huskers took a 2-0 lead in the bottom of the second on three walks by Tech starter Nathan Fouts and a two-out RBI single by Jeff Leise.
Nebraska took a 3-0 lead in the fourth inning on an RBI single by Daniel Bruce that plated Brandon Eymann who reached on a leadoff walk.
Alvarez got a one-out single in the top of the seventh inning to give him a career-high 12-game hitting streak.
Senior designated hitter Nick Blankenship plated Tech's only run of the game when he connected on a solo home run to left-center field.
The home run was Blankenship's 12th this season and kept Tech's streak of 12 straight games in which the team has hit at least one home run.
Nebraska All-American Shane Komine improved to 5-0 this season with the victory. Fouts (5-3) suffered the loss for Tech after surrendering two earned runs on four hits and four walks.
The Raiders (20-11, 4-6) and Nebraska will meet in a doubleheader on Saturday at 11:30 a.m.