The triangle of information shown in this learn node is a phase diagram thermodynamic calculation for solder Bi-Pb-Sn. So who care about something like that? In the advancing complexity of metallurgy, depth of detail is important. This is the explanation of the NIST host of the diagram, whose Web site explains the mission:

The NIST Metallurgy Division is working closely with materials suppliers and users to develop the measurement and standards infrastructure needed in diverse technological areas – from steelmaking to the fabrication of nanostructured multilayers for magnetic recording heads. . . .

Learning about solder might seem more likely to involve technique, like that offered in the PDF which contains the illustration of “Tinning the soldering iron” from About Soldering—making Clip Leads—CLK from MIT’s Open Courseware. A sample of third sort of soldering knowledge available online is this popular Soldering Guide, a tutorial supported by Google ads.

Within the open Internet, patterns of related ideas for the subject of solder can be an amalgam from diverse sources.

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The sketch in this learn node is from a course taught at MIT. You can virtually sit in on the lectures from the course by clicking this link: Fundamental Concepts of Material Science. The above sketch is from page 7 of lecture L2 PDF that you can download from the list you will get when you click the link. The sketch teaches us:

Mixture: Inhomogeneous multi-phase system where the components are not mixed on a molecular level.
Solution: Homogeneous system, components are mixed on a molecular level.

The difference between a solution and a mixture is a basic idea that the illustration above gives us � so that we can go on in our own learning to other concepts linked to the subject. The PDF of the lecture is an excellent place to move on in this learning; it has 13 pages of basics. The elemental new power of learning in the network ecology online is a matter of grasping a node like this one about “mixture or solution” and linking to related nodes to build concepts and experience thinking.

MORE LEARN NODES about mixtures and solutions from Rice University: “The word mixture can be defined as a heterogeneous association of substances that cannot be represented by a single chemical formula. This definition does not limit mixtures to solids mixed with liquids, nor is every mixture considered to be a solution. . . .”

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