science

Permendur

Permendur is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Permendur rather than just read about it. In short: Permendur is a cobalt-iron soft ferromagnetic alloy with equal parts of cobalt and iron which is notable for its high magnetic saturation level. Its saturation flux density of around 2.4 tesla is the highest of any commercially available metal.

Key takeaways

Permendur belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Permendur to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Permendur from memory before moving on to harder problems.

Reference excerpt

Permendur is a cobalt-iron soft ferromagnetic alloy with equal parts of cobalt and iron which is notable for its high magnetic saturation level. Its saturation flux density of around 2.4 tesla is the highest of any commercially available metal. Coupled with its low coercivity and core losses, its high saturation and permeability makes Permendur useful as magnetic cores in transformers, electric generators and other electrical equipment. The advantage of high saturation in a magnetic core is that it can function at higher magnetic field strengths, so the core can be smaller and lighter for a given magnetic flux and power level. Permendur is used for magnetic cores and pole pieces in lightweight transformers and electric motors used in aircraft. The alloy was invented in 1929 by Gustav Elmen at Bell Telephone Laboratories. Various formulations are sold under different trade names. Cobalt-iron alloys like permendur have very high Curie temperatures so they can function magnetically at high temperatures at which other ferromagnetic materials lose their magnetic properties. They are harder and less ductile than many other iron alloys and so are harder to fabricate, but have superior mechanical strength. Most permendur alloys require heat treatment after fabrication to attain the best magnetic properties. The most important alloys are

Permendur 2V (Vanadium Permendur, Permendur 49): Invented by White and Wahl in 1932, it is approximately 49% cobalt, 49% iron and 2% vanadium. The vanadium improves ductility and workability. Supermendur (Hiperco 50): Invented by Gould and Wenny in 1957, it has similar composition to Permendur 49 but is grain-oriented so it has a square hysteresis loop and much lower core losses, for better performance in transformers. Current formulations include trace amounts of niobium, silicon and manganese to improve cold-forming properties. The coercivity can be controlled by varying the vanadium concentration. Equiatomic cobalt-iron alloys with more vanadium than permendur, 2-5%, are called Remendur. This is a medium-coercivity magnet material which bridges the gap between Permendur and Vicalloy cobalt-iron magnets with 8-15% vanadium.

References

Illustrations

Worked examples

Example 1 — a first encounter with Permendur

Start with the simplest possible case. Write down what Permendur claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Permendur before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Permendur ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Permendur

In research: Permendur appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Permendur in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Permendur is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alloy stubs, Cobalt alloys, so understanding it makes those chapters shorter.
In everyday life: Look for Permendur outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Permendur in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Permendur means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Permendur out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Permendur in simple terms?

Why does Permendur matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Permendur?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Permendur.