Well, assuming you mean the philosophical materialism, I'd say there is likely an overlap between materialists and atheists. However, as you've read on Quora, Atheism is the absence of a belief in a god or gods. read more
Materialism implies atheism to a degree. It is hard to imagine gods if nothing exists beyond the physical. Atheism, depending on your definition of gods, may not imply materialism. If you feel no personal God exists, you may still believe in forces beyond the natural. read more