Sue,
Scintered (sic) metal castings are nothing new. And they can be very strong and durable. Winchester started making the receivers for the 94s lever guns from scintered metal in 1964. The powdered metal was mixed with a binder then put into a mold and super heated to melt the metal. The resulting part needed much less final machining and fitting, thus reducing costs. This was continued until about 1981. There is no lack of strength or durability with them. The only problem is this type of metal will not take a normal chemical bluing.
MIM, ( Metal Injection Molding ) is another form of manufacturing where powdered metal is used with a binder or catalyst to make parts. Again strong and durable.
I doubt it matters how the powdered metal is shaped as long as the proper heating and heat treating is done with the finished part.
Joe