A downhole tool includes a housing configured to be placed into a subterranean environment and a mixer disposed in the housing. The mixer includes a first inlet configured to receive a fusible metal or alloy component and a second inlet configured to receive a solid metal or semi-metal component. Additionally, the mixer includes a mixing chamber configured to mix the fusible metal or alloy component and the solid metal or semi-metal component to form a liquid or partially liquid alloy. Further, the mixer includes an outlet configured to discharge the liquid or partially liquid alloy into the subterranean environment. The liquid or partially liquid alloy is configured to harden into a solid alloy over time.