This settling into layers is called sedimentation. In microgravity, sedimentation is reduced, so that when the melted metal cools, particles are evenly distributed throughout the metal, improving its strength. On LMS, scientists not only successfully mixed particles into metals, they also observed what would happen to the particles if the melted metal containing them was cooled very slowly. They found that the particles were pushed out of the metal as it cooled, instead of being captured in it. The force of Earth's gravity extends far into space.
Weight is the force with which a body is attracted to the Earth.
Any object in a state of freefall experiences microgravity, or near weightlessness. An orbiting spacecraft is actually falling around the Earth. The spacecraft's altitude and speed cause its fall to match the curvature of the Earth, so that it never hits the Earth but continually orbits the planet. All objects carried by an orbiting spacecraft are also in a state of freefall.