Công nghệ cơ khí thường tạo ra các giả lập mô phỏng hoạt động của các đối tượng, như quy trình chế tạo thực tế theo trình tự tối ưu hóa sự thực hiện, hiệu quả kinh tế và chi phí năng lượng trước khi quyết định lựa chọn một thiết kế cụ thể. Các bản vẽ kỹ thuật để chế tạo là sản phẩm cuối cùng của khâu thiết kế. Chúng phải thỏa mãn hai mục đích: bao gồm đầy đủ tất cả các thông tin cần thiết để chế tạo và cũng còn là một tiêu chí kiểm soát. | 190 The Coming of Materials Science reason and recognise that at high temperatures grain boundaries are fragile that heat-treatment involving hot or cold work coupled with annealing can lead to benefits in some instances and to catastrophes such as hot shortness in others this term means brittleness at high temperatures . Advances in technology and practice do not always require exact theory. This must always be striven for it is true but a hand-waving argument which calls salient facts to attention if readily grasped in apparently simple terms can be of great practical utility. This controversial claim goes to the heart of the relation between metallurgy as it was and as it was fated to become under the influence of physical ideas and more important of the physicist s approach. We turn to this issue next. As we have seen Rosenhain fought hard to defend his preferred model of the structure of grain boundaries based on the notion that layers of amorphous or glassy material occupied these discontinuities. The trouble with the battles he fought was twofold there was no theoretical treatment to predict what properties such a layer would have for an assumed thickness and composition and there were insufficient experimental data on the properties of grain boundaries such as specific energies. This lack in turn was to some degree due to the absence of appropriate experimental techniques of characterisation but not to this alone no one measured the energy of a grain boundary as a function of the angle of misorientation between the adjacent crystal lattices not because it was difficult to do even then but because metallurgists could not see the point of doing it. Studying a grain boundary in its own right - a parepisteme if ever there was one - was deemed a waste of time only grain boundaries as they directly affected useful properties such as ductility deserved attention. In other words the cultivation of parepistemes was not yet thought justifiable by most metallurgists.
