In short, yes, milk can substituted for heavy cream in an ice cream recipe. In fact, if you want to save a trip to the grocery store, milk, half and half, light cream, heavy cream and whipping cream can all be substituted for one another. However, each substitution will change the texture and taste of your finished ice cream product.
At a molecular level, the main difference between all these creams is the fat content. The higher the fat content, the thicker and creamier the resulting ice cream will be. Generally, if you are looking for a substitute, it’s always a safe bet to go for a cream with a higher fat content. On the other hand, milk and light cream are great substitutes for heavier creams if you’re hoping to cut calories from a recipe, but the ice cream will be less thick and creamy, and more grainy and icy.