Two alloys, ten specimens per test

Materials science poster

A materials science poster is read composition first, so this A0 portrait example puts the weight percent line at the top of its methods protocol where a metallurgist looks for it. Two charts split the two properties: tensile results in one, hardness and the measured silicon length in the other, with the 14 percent strength gain as the key number.

Create a poster with OneCraftA0 Portrait, printed at 841 by 1189 millimetres

The whole board

The poster at full size, exactly as it prints. Every number, citation and caption on it was written for this example, so the layout is being judged on real content.

FU
Strontium modification raises the tensile strength of an Al-7Si casting alloy by 14 percent without loss of hardness
J. Okoro ¹, V. Marchetti ¹, D. Yilmaz ²
1 Department of Materials, Fenwick University · 2 Fenwick Foundry Services
Abstract
Strontium modification is the cheapest change a foundry can make to an aluminium silicon casting alloy, a 0.03 percent addition to the melt, and its reputation rests mostly on textbook micrographs rather than paired mechanical data. We cast a reference Al-7Si-0.3Mg alloy and the same alloy with 0.03 percent strontium under identical permanent mould conditions, heat treated both to T6, and tested ten specimens per alloy for tensile properties and hardness. Ultimate tensile strength rose from 218 to 249 MPa, a 14 percent gain, while Brinell hardness was unchanged at 78 against 80 HB. Elongation more than doubled, from 2.1 to 4.6 percent, and the eutectic silicon length fell from 18.4 to 4.1 micrometres, which is the mechanism doing the work. The gain arrives through ductility, not through a harder matrix.
Why modification matters
Unmodified Al-7Si solidifies with its eutectic silicon as long brittle plates, and every one of those plates is a crack waiting for a load. A casting that fails at 2 percent elongation fails without warning, so designers derate the alloy far below what its composition could carry. Strontium changes the silicon from plates to fine fibres without changing the chemistry that sets hardness, which raises the pair of questions this study answers with paired castings: how much tensile strength does the finer silicon buy, and is any of it paid for in hardness? The suspicion that modification trades hardness away persists in foundry practice despite little published evidence either way, and it decides whether parts that see wear can be modified. Both properties were therefore measured on the same castings, from the same melts, by the same operators, so the comparison on this board carries no batch effect.
METHODS
Composition. Wt percent: Si 7.0, Mg 0.32, Fe 0.12, Sr 0.03 (modified) or none (reference), balance Al; checked by spark spectrometry on every melt.
Casting. Permanent mould, 720 C pour temperature, both alloys cast in the same session; T6 heat treatment: 535 C for 8 h, water quench, 170 C for 6 h.
Tensile. Ten specimens per alloy, 6 mm gauge diameter, crosshead 1 mm per minute, per the standard tensile method for metallic materials.
Hardness. Brinell, 2.5 mm ball at 62.5 kgf, ten readings per alloy on polished sections away from porosity.
Microstructure. Optical microscopy at 200x; eutectic silicon length measured on five fields per alloy by line intercept.
Modified 0.03% Sr
Reference
UTS
Yield
Elongation
065130195260
Figure 1. Tensile properties in MPa, mean of 10 specimens per alloy. Elongation is plotted as percent x 10 to share the axis.
Source: Trial dataset, 2026.
Results
Ultimate tensile strength rose from 218 MPa (SD 9) in the reference alloy to 249 MPa (SD 8) with strontium, a difference of 31 MPa (95% CI 22 to 40, p < 0.001). Yield strength moved from 172 to 178 MPa, a 6 MPa difference that did not reach significance, which is what the mechanism predicts: modification changes the silicon, not the age hardened matrix that sets yield. Elongation more than doubled, from 2.1 percent (SD 0.5) to 4.6 percent (SD 0.7), and it is this extra ductility that lets the modified alloy work harden its way to a higher ultimate strength before fracture. Brinell hardness was 78 HB (SD 3) in the reference alloy and 80 HB (SD 3) modified, a 2 HB difference well inside measurement error and not significant. The suspicion that modification softens the alloy is not supported at any point in this series: no single modified reading fell below the reference mean. The microstructure closes the loop. Mean eutectic silicon length fell from 18.4 micrometres in the reference alloy to 4.1 micrometres with strontium, and the fracture surfaces changed to match: reference specimens failed through cracked silicon plates, while modified specimens showed ductile dimples around fine fibres. Every mechanical difference on this board is downstream of that one change of shape, and the composition line in Methods is the entire cost of producing it. Porosity, measured on the polished hardness sections, did not differ between alloys, so the comparison is not confounded by casting quality, and no specimen in either group failed outside its gauge length.
Modified 0.03% Sr
Reference
020406080
Brinell hardness (HB)
Silicon length (micrometres)
Figure 2. Hardness is unchanged at 78 against 80 HB while the eutectic silicon length falls from 18.4 to 4.1 micrometres.
Source: Trial dataset, 2026.
+14%
ultimate tensile strength with 0.03% Sr
249 against 218 MPa, n = 10 per alloy, 95% CI 22 to 40 MPa
Discussion
The pattern of what moved and what did not is the finding. Strength rose only where ductility could carry it: ultimate strength up 14 percent, yield effectively unchanged, elongation doubled. That is the signature of a silicon morphology effect rather than a matrix effect, and it means the gain is real load bearing capacity in a casting that now deforms visibly before it fails, which matters as much as the number itself for parts where failure must announce itself. Hardness deserves its own sentence because it drives shop floor decisions. At 78 against 80 HB the two alloys are indistinguishable to any acceptance test a foundry runs, so a wear rated part loses nothing by being modified, and the reason is mechanical: hardness in this system is set by the T6 aged matrix, which strontium does not touch. The limits are those of a single controlled series. Ten specimens per alloy came from one heat each, cast on one day in one mould, so melt to melt variation is not measured here, and permanent mould cooling rates are faster than sand casting, where unmodified silicon grows coarser and the gain from modification is usually larger. These results are therefore a conservative floor for sand foundries rather than a ceiling. Fatigue, the property most sensitive to silicon plates, was not tested; a rotating bend series on the same two alloys is the obvious next step and the specimens are already cast.
CONCLUSION
A 0.03 percent strontium addition buys 31 MPa of ultimate strength and double the elongation at no cost in hardness. For this alloy the case for modifying every structural melt is now a measured one, and the fatigue series that would complete it is already cast.
UTS 249 against 218 MPa, a 14 percent gain
Hardness 80 against 78 HB, no change
Elongation 4.6 against 2.1 percent
Silicon length cut from 18.4 to 4.1 micrometres
REFERENCES
1.Okoro J, Marchetti V. Strontium modification of Al-Si casting alloys: a mechanical survey. Journal of Casting Research 2024;22(3):145-162.
2.Yilmaz D, Okoro J. Eutectic silicon measurement by line intercept: repeatability across operators. Metallography Notes 2023;9(2):77-90.
3.Marchetti V, Sato H. Tensile testing of permanent mould castings: specimen location and porosity. Foundry Practice Review 2025;13(1):30-46.

Block by block

What each block on the board is for, in the order a reader walks it.

Title band and authors
The title makes the claim and its boundary in one line: strontium modification raises tensile strength by 14 percent without loss of hardness. The foundry that cast the specimens is the second affiliation, and the QR code carries the micrographs the board cannot.
Abstract and introduction
The abstract pairs every claim with its numbers: 218 to 249 MPa, 78 against 80 HB, elongation 2.1 to 4.6 percent, silicon length 18.4 to 4.1 micrometres. The introduction explains why the hardness question decides foundry practice for wear rated parts, which is the reason the study exists.
Methods: composition first
The first protocol entry is the composition line, Si 7.0, Mg 0.32, Fe 0.12, Sr 0.03 or none, balance Al, checked by spark spectrometry on every melt. Casting conditions, the T6 schedule, both test methods and the microstructure measurement each get one labelled entry after it.
Tensile properties (Figure 1)
Grouped vertical bars compare the two alloys on UTS, yield and elongation, with elongation plotted as percent times ten so it shares the MPa axis, a scaling the caption states. The pattern is the argument: ultimate strength up, yield level, elongation doubled.
Results
The results text carries the statistics the bars cannot: the 31 MPa difference with its interval of 22 to 40, the non significant 6 MPa yield change, and the porosity check that clears casting quality as a confounder. Standard deviations for every mean are printed with their n of ten.
Hardness and silicon length (Figure 2)
The second chart holds the two numbers that close the argument: hardness at 78 against 80 HB, unchanged, and eutectic silicon length cut from 18.4 to 4.1 micrometres. Reporting the microstructure as a measured length turns the mechanism into a checkable number instead of a picture.
The key number
The stat block prints plus 14 percent, ultimate tensile strength with 0.03 percent strontium, over the detail line of 249 against 218 MPa, n of 10 per alloy and the 95 percent interval. One number headlines; the rest of the board is its supporting evidence.
Discussion, conclusion points and references
The discussion explains why the gain arrives through ductility, why permanent mould results are a conservative floor for sand foundries, and that fatigue was not tested. The three references are invented for this fictional study, because the reference block is required on this layout; on your board, replace them with your sources.
How to adapt this board
Make your two materials the two series on both charts and keep that order identical everywhere so the colours mean the same thing all down the board. Put composition in the first protocol entry, report the microstructure as a measured quantity, and headline the one property your audience buys the material for.

What makes this board work

Two properties, two charts

Tensile results fill Figure 1 and hardness with silicon length fills Figure 2, so neither is squeezed into a corner of the other and each chart answers one question at a metre.

Composition where a reader looks

The weight percent line, Si 7.0, Mg 0.32, Fe 0.12, Sr 0.03, is the first methods entry. A metallurgist reads composition before believing any property, and this board does not make them hunt.

The mechanism is a number

Eutectic silicon length cut from 18.4 to 4.1 micrometres links the microstructure to the 31 MPa strength gain without a single micrograph, and it is a value another lab can measure and compare.

Questions people ask

What goes on a materials science poster?

Composition, processing route, the test standards, the measured properties with their scatter, the microstructure result and the comparison that motivates it all. This board runs exactly that order, and its one structural choice is splitting tensile and hardness into separate charts.

Can I show micrographs?

No poster layout has a fillable image slot, so this board reports the feature the micrograph would show as a measurement, silicon length from 18.4 down to 4.1 micrometres by line intercept, and links the images from the QR code. A measured length also travels between labs better than a picture.

How do I present composition without a table?

One protocol entry with the weight percent values in a single line works for five elements, which is what this board does. If your system needs a full composition table, the table led layouts carry an eight row table, but you give up this layout’s second figure to get it.

Which chart kind for tensile results?

Grouped vertical bars, one group per property and one bar per material. The figure slot accepts ten chart kinds, and bars beat lines when the x axis is categorical. This board scales elongation by ten to share the MPa axis and says so in the caption, which is the honest way to mix units.

Should I cite the test standards?

Yes, in the methods entries where each test is described, with the full citations in the reference list. This board names the tensile method, the Brinell conditions, 2.5 mm ball at 62.5 kgf, and the measurement technique for silicon length, so every number has a named procedure behind it.

How many specimens should I state?

The n for every mean, everywhere the mean appears. This board prints n of 10 per alloy in the captions, the results text and the stat detail, and the discussion says all ten came from one heat per alloy, which is the limit a materials reviewer will want acknowledged.

Build your own in about a minute

The button below opens the generator with this use case already described. Change the wording to match your own, generate, then edit anything you like.

Make my materials science poster

Other poster examples

Sociology research poster example

Forty eight interviews with renters about why they stop reporting repairs, laid out as an A0 portrait board that leads with the question rather than the finding. The headline is the question a passer by can answer in their head, and the four reasons sit underneath in the renters own words.

Engineering test poster

An engineering poster is read the way a test report is read: rig, standard, tolerances, then the table of what broke and how. This A0 landscape example puts eight of twelve beam specimens in a failure load table, one load against deflection curve per beam type, and the plate and screw tolerances in the methods block.

Social work research poster example

Twelve months of routine time records from 84 caseworkers in six offices, laid out as an A0 portrait board with three icon topped key points across the top. The board answers one question a manager can act on: what a caseload of thirty costs in client contact.

Want the steps in the builder? Read Add charts and diagrams, then choose the template, theme and size. For everything this generator can do, see the poster maker.

Sources

Written and checked by the OneCraft team. Last checked .