Alpha said Uranium One Holding, a subsidiary of the Russian State Atomic Energy Corporation, would invest an initial $30 million for a 15% stake in Tolillar.
Uranium One could earn another 35% for $185 million, after milestones were achieved including a 5 tonne per annum pilot plant and a feasibility study.
If Uranium One exercised this earn-in right, it would become operator and control Alpha's board, the proceeds would fund a 10,000tpa plant and it would gain marketing rights.
Alpha president and CEO Brad Nichol said under the deal, the junior would retain a 50% interest in the project.
"This early-stage asset has attained a truly game-changing breakthrough for our shareholders," he said.
"This sort of milestone is rarely achieved by a company with less than two years of operations and with a valuation at this level.
"Exercising the earn-in right implies a value at Tolillar of $529 million, not including any additional consideration."
Uranium One president Andrey Shutov said in a joint statement the deal was aligned with its strategy of acquiring non-uranium mineral resources and represented a scaled approach to lithium production.
Alpha said the transaction was limited to Tolillar and was expected to leave Alpha with about $45 million in cash, which it planned to use on its nearby assets in the Salar del Hombre Muerto.
Alpha had reported a loss of C$2.6 million for the three months to September 30.
It announced an upsized bought-deal offering earlier this month of $21.75 million, priced at $1 per unit.
Its shares (TSXV: ALLI) closed up 20.3% yesterday to $1.48, taking this year's gains to almost 120%, and valuing it at $184 million (US$144 million).