MS&E ranges from how to make "something" from some set of raw materials (or feed-stock), to finding the reasons why the "thing" failed in service. It deals with specifying the "best" composition, nanostructure and micro-structure for the desired application. It deals with specifying the "best" surface treatment to separate the "thing" from its environment. It can deal with at least some part of "life-cycle" costs, whereby one tries to determine the total cost (dollars, energy, etc.) of an object throughout its lifetime.
MS&E is multi-disciplinary. If "something" is a metal: the study is called metallurgy or metallurgical engineering. If "something" is a ceramic: the study is called ceramics or ceramic engineering. If "something" is a polymer: the study is called polymer science or engineering.
MS&E has been guilty of not taking charge of topics under its jurisdiction. Some examples. If "something" is a composite (mixture of the above): the study is usually called something like composite engineering. This teaching of this study might be in housed mechanical engineering, it might be housed in chemical engineering, in a materials science and engineering department, or somewhere else. Housing it in mechanical engineering often will put much more emphasis on production methods. Housing it in a department devoted to one specific matrix (for example polymer matrices with chemical engineering) often leads to de-emphasis of the other kinds of matrices (metal or ceramic).
If "something" involves conductors, semi-conductors and resistive materials: it is called solid-state physics. It could be housed in physics, electrical engineering, computer engineering or in engineering physics.
MS&E involves measurement, and the analysis of measurements. And hence, statistics. Sure, there are the simple type of statistics, like finding the average of some scalar quantity like bulk density. But, there can be so much more. Many properties and effects of interest are not scalars, but are actually described by tensors. How do you average a tensor property over a volume (or mass)? Surfaces are also important, for physics and chemistry reasons.
MS&E deals with failure. We (society, or technology) may not understand the composition and structure well enough, and so the item fails before its intended service life has passed. We may not understand how the material interacts with its environment, which can bring about failure by corrosion, erosion, spalling, wear, etc. Generally some kind of environmental attack.
Too often, the choice of material is made by default (we only have 1014 steel, so we made it out of that) or a non-materials engineer picks something out of a table of properties. A mechanical engineer spends at least 4 years studying to do his job, as does the materials engineer. Why is it assumed that picking the material to build something out of is so trivial? Projects are becoming multi-disciplinary (concurrent is another term), why not get a materials engineer involved in specifying materials? Quality and consistency should only improve with using near-optimal materials along with your near-optimal design.
One reason why various materials disciplines end up outside of materials departments, is that historically materials departments have not had the mathematical or first principles physics and chemistry background to be effective. Most of the materials disciplines evolved in a very pragmatic way. This was probably natural, as the first principles science and mathematics for most problems tends to be more difficult than is seen in other engineering disciplines.
Above I make a strong statement about choosing materials. Current practice has evolved with non-materials engineers usually choosing materials essentially by table lookup. That no serious problems have been traced to this practice, must mean it works fine?
I can appreciate that what material to make something out of, at least tentatively, needs to be approximately made very early in the design phase (mechanical, civil, electrical, ...), and then firmed up at the end by a specific choice. A common initial assumption is that everything is made of "jellium", an isotropically elastic material with the density and Young's modulus of steel.
There are at least 2 things which point to the current system not being adequate. In no particular order:
In the case of updated materials use in a replacement design of a part or group of parts, there has to be benefits to the new design (and new materials), otherwise the update would never have been published. But one wonders how much could have been saved if this design had of been implemented first, instead of being retrofit?
The products of engineering are made of real materials. A homogeneous design will have all parts of the product being made of the "same" material. It is entirely possible that while someone assumed that part A and part B are made of the same material, that they do have differences in grain size, that the differences in grain size are a function of location, and that there are differences in texture (orientation of the grains).
There are no elastically isotropic, single grain solids. Glasses may be elastically isotropic, but there are arguments for treating glasses as liquids in design. In multi-grained materials, we can obtain statistical, elastic isotropy in some cases. Nanomaterials (materials composed of grains that are nearly as small as atomic distances, few atoms or molecules per grain) would be a limiting case of a fine grained material. If a design relies on statistical, elastic isotropy; a change in process can lead to a breaking of isotropy. This problem will be more prevalent as part dimensions approach the grain size in the part.
Changing how a part is made or finished, changing the supplier of a part, the supplier changing how the part is made or finished, or the material that the part is made of, etc. can lead to changes in performance of the finished design.
Very few material properties are a simple, scalar constant in a linear equation. In general, materials properties are tensors. If more than one kind of material property is important to a design, it is possible that the material behaves with different symmetry with respect to the different materials properties.
If we allow for heterogenous designs, we introduce interface considerations and we may be introducing the possibility of chemical reactions taking place. This is added to all the complications which come from properly considering materials engineering in a homogenous materials design. Some materials wear well against each other, some don't. Different materials have different properties, and symmetries of those properties. A stiffer material will shield stress from a less stiff material, localising contact forces. Differing chemical potentials can lead to various kinds of corrosion or oxidation, or drive diffusion.
That engineering can continue to function as it currently does is obvious, serious materials driven problems do not seem to be occuring. However, getting materials engineering into the design process at the beginning can lead to improvements in performance, in front-end production costs, and in life-cycle costs. It is improvements in materials engineering which has driven, and will continue to drive advances in computer hardware, sensors and many other things. Materials science and engineering can provide valuable input, but you need to ask for it.