Answer:
Heterogeneous mixture
Step-by-step explanation:
A mixture is a combination of materials that are combined solely by physical processes. There are two types of mixtures heterogeneous and homogeneous.
Homogeneous mixture is a mixture that has uniform composition of their components. Composition of a substance means color, shape, size, weight etc.
Heterogeneous mixture is a mixture that does not have uniform composition of their components.
Steel is an alloy which is a combination of iron and carbon. The composition of iron and carbon is not uniform, so the mixture is a heterogeneous mixture.