--- title: "CHART: Permeability of Popular Iron Powder Types" description: This article & chart are a look at magnetic permeability. If you're struggling to get a quick response to an applied current in your product, try raising permeability. Let’s look at how different tiers of iron powder materials -- and the strong permeability of iron powder -- boost part performance. image: https://www.horizontechnology.biz/hubfs/iron%20powder%20types.jpg --- # CHART: Permeability of Popular Iron Powder Types. Posted by Horizon Technology - March 07, 2019 - [**](https://www.facebook.com/sharer/sharer.php?u=https://www.horizontechnology.biz/blog/iron-powder-types-permeability) - [**](https://www.linkedin.com/shareArticle?mini=true&url=https://www.horizontechnology.biz/blog/iron-powder-types-permeability&title=&summary=&source=) - [**](https://twitter.com/home?status=) - [**](https://plus.google.com/share?url=https://www.horizontechnology.biz/blog/iron-powder-types-permeability) - [**](mailto:?&subject=https://www.horizontechnology.biz/blog/iron-powder-types-permeability&body=https://www.horizontechnology.biz/blog/iron-powder-types-permeability) ** This article -- and this chart -- are a look at magnetic permeability. “Permeability” refers to how easily a material can be magnetized. If you’re having an issue getting a quick enough response to an applied current in your product, increasing the permeability is likely your answer. Let’s look at how different tiers of advanced iron powder materials -- and the strong permeability of iron powder -- level up your component’s performance. Consider this a reminder that you can upgrade from your [old standby material](https://www.horizontechnology.biz/blog/powder-metal-materials-iron-copper-carbon) and get even better performance than you thought possible with powder metal! ## Permeability of Iron Powders ![iron powder chart](https://www.horizontechnology.biz/hs-fs/hubfs/iron%20powder%20chart.jpg?width=825&name=iron%20powder%20chart.jpg) The chart above shows the permeability of three sintered powder metal soft magnetic materials: Pure iron, iron-0.45% phosphorus, and iron-3% silicon. Both the iron-phosphorus and the iron-silicon were produced by adding either an iron-phosphorous or iron-silicon master alloy. Alloying the iron with either phosphorus or silicon **increases the permeability** (how efficiently a material is magnetized by an applied current). Thus, if faster magnetic response -- for, say, a solenoid or an actuator -- there are three options: 1. Increasing density 2. Using phosphorus or silicon alloying systems 3. Merging #1 and #2 together A great example of this is structural powder metals, where you need strength **and** temperature resistance **and** lubricity. By taking Door No. 3 above, you can get the synergy of both effects. *(****DYK?**** Induction -- when magnetism is produced via the subject’s exposure to a magnetic field -- is merely a function of density. Higher density = higher induction.) * ## About These Types of Iron Powder ... The three [ferritic metal powders](https://www.horizontechnology.biz/blog/ferrous-powder-vs-nonferrous-material) are represented on this line chart provide a good point of reference for using iron-based metal powder. Here’s the speed dating version of each variety. (Of course, there are other advanced PM materials out there, too.) [**RELATED: Expanded flow chart of powder metal materials **](https://www.horizontechnology.biz/blog/powder-metal-materials-flow-chart) ### Pure Iron Pure iron, represented by the blue line, is the basis for most mixes of low-alloyed sintered steels. High-purity iron has good [soft magnetic qualities](https://www.horizontechnology.biz/blog/soft-magnetic-composite-what-is). A vendor can use coated or insulated iron to add new design options -- just keep in mind that resistivity in pure iron is quite low. ### Iron-Phosphorus Iron phosphorus, depicted as the orange line, boasts high: - Induction - Strength - Hardness - Ductility The resistivity of iron-phosphorus is better than that of pure iron, but still not optimal if that’s a big concern of yours. ### Iron-Silicon Iron-silicon, the black line on the chart, has the **highest maximum permeability** of these three options. Iron-silicon sintered parts respond better to moderate frequencies than their iron-phosphorus counterparts. It’s also favored for its solid impact resistance. ## Sintering Iron A brief word about the sintering of the three materials on this chart: Both pure iron and iron-phosphorus powder can be sintered at a “normal” sintering temperature of 2050 degrees F. However, iron-silicon powder requires a **minimum sintering temperature of 2300 degrees** to fully realize the benefits of added silicon: - Full homogenization/uniformity - Increased density - Optimal magnetic response Temperatures above 2300 degrees F will produce even better magnetic results. This advanced technology is only available at a select few powder metal parts manufacturers. ## Outside the Box Isn’t a Bad Thing The same performance analogy can be drawn not only from magnetic response, but also any other mechanical property. Remember, you can choose a better alloy, you can choose to bump up density, or you can choose **both**. And you can subsequently add in other characteristics by including other elements (lubrication, etc.). Don’t let your mind get stuck on the [MPIF Standard 35 materials](https://www.mpif.org/News/TabId/164/ArtMID/586/ArticleID/123/New-MPIF-Standard-35-Materials-Standard-Released.aspx). The box is the MPIF Standard 35. [Thinking out of the box](https://www.horizontechnology.biz/blog/powder-metal-1p-3p-5p) can improve your part's performance. All it takes is the courage to do powder metal differently. 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