By Ankit SinghReviewed by Lexie CornerApr 25 2025Thixotropy is a lesser-known but crucial material property in modern manufacturing. Derived from the Greek words thixis (touch) and tropos (turning), it refers to materials that temporarily lose viscosity under mechanical stress and then gradually regain it when left undisturbed.
This reversible flow behavior helps bridge the gap between solid and liquid states, enabling precise control over how materials move and settle.1
Image Credit: Nordroden/Shutterstock.com
Understanding thixotropy is especially important in industries that use advanced metal-forming techniques. One key example is semi-solid metal processing, which takes advantage of thixotropic behavior to produce lightweight, high-strength parts for electric vehicles and aerospace systems.2,3
In this article, we explore what thixotropy is, where it shows up in industry, and why it matters for improving both processing efficiency and product performance.
What is Thixotropy?
Thixotropy is a time-dependent rheological property where a material’s viscosity decreases under shear stress and then gradually recovers when the stress is removed. When movement stops, the material thickens again over time.
This behavior differs from simple shear thinning, where viscosity drops immediately under stress and returns as soon as the stress is removed. Because thixotropic materials take time to recover, they are ideal for processes that require easy shaping or pumping followed by stable resting behavior.1,4
How Thixotropy Differs from Other Flow Behaviors
- Shear Thinning vs. Thixotropy
Both involve a reduction in viscosity under stress. However, in shear thinning, the effect is instantaneous and fully reversible—like ketchup, which becomes runnier when shaken and stays that way instead of thickening again immediately.
In contrast, thixotropic materials, such as semi-solid magnesium alloys, take time for their microstructure to reform and their viscosity to recover.4
Pseudoplasticity is often confused with thixotropy. Pseudoplastic materials, like toothpaste, also thin under stress but do not regain their original thickness after the stress is removed.4,5
Rheopexy is the opposite of thixotropy. Here, materials thicken when stress is applied, such as in mixtures of cornstarch and water.4
In thixotropic metals such as aluminum or magnesium alloys, solid globular particles are suspended in a liquid matrix. When stirred or deformed, these particles align to lower the material’s viscosity. Once at rest, they reagglomerate, restoring the material’s original structure and strength.5
Thixotropic Mud Demonstration
Where Does Thixotropy Show Up in Manufacturing?
Thixotropy is an important property in industries where controlling material flow during processing (and maintaining stability afterward) is crucial.
Semi-Solid Metal Processing (Thixoforming)
Thixoforming involves heating metals to a semi-solid state (40–60 % solid) and injecting them into molds. This method, used for aluminum and magnesium alloys, minimizes defects like porosity and shrinkage seen in traditional die casting.
For instance, Jeep Wrangler spare tire carriers and lightweight automotive suspension components are thixomolded to achieve high strength-to-weight ratios.3,6
Metal Injection Molding Feedstocks
Metal Injection Molding (MIM) combines powdered metals with plastic binders to create complex, small-scale components.
These feedstocks are thixotropic, meaning they flow easily when injected into molds but set quickly once in place—a critical feature for producing precise parts like surgical instruments and firearm components.7
Additive Manufacturing (3D Printing)
Thixotropic metal slurries are essential in advanced 3D printing methods like binder jetting and directed energy deposition. Recent breakthroughs have produced thixotropic high-entropy alloys (HEAs) for aerospace applications.
These novel materials demonstrate the ability to maintain fine microstructures while exhibiting superior mechanical properties like greater strength, ductility, and heat resistance.7,8
Coatings and Conductive Pastes
Metal-based paints and solder pastes rely on thixotropy for smooth application and resistance to sagging. For example, conductive inks used in printed electronics must flow easily through nozzles while resisting unwanted spreading after application.9
Download your PDF copy now!
Why Thixotropic Behavior Matters in Industrial Processes?
Material Flow and Mold Filling
Semi-solid metals flow smoothly due to their thixotropic behavior, which helps minimize air entrapment during injection. Operating at lower temperatures also improves energy efficiency, reduces thermal stress on molds, and extends die life. Thixoforming further supports near-net-shape manufacturing, saving material and labor costs.3,6
Pumpability and Process Flow
In battery manufacturing, thixotropic electrolytes stay thin when pumped but prevent particle settling during storage. In oil and gas operations, drilling fluids exploit thixotropy to ease pumping and maintain borehole stability when static.10
Surface Finish and Dimensional Accuracy
Thixotropic materials fill complex molds smoothly, improving the surface finish and structural integrity of final parts. A study on AlCoCrCuFeNi high-entropy alloys found that thixoforming eliminated dendritic structures, resulting in tensile strengths higher than those of cast equivalents.7
Material Stability and Recovery
In 3D concrete printing, thixotropic cement pastes help maintain shape after extrusion, a key requirement for building vertically without collapse before curing.
Similarly, semi-solid metals regain viscosity after being injected into molds. This helps prevent distortion during cooling. As they shift from liquid to solid, they retain just enough flow to fill complex mold shapes while holding their final form.3,10
Sustainability
Thixoforming supports more efficient manufacturing by enabling near-net-shape production, which significantly reduces material waste.
For example, Idra’s innovative Thixotropic Piston Injection (TPI) process recycles magnesium scrap into high-quality auto components. It also lowers CO₂ emissions, offering a more sustainable alternative to conventional casting methods.2
How Is Thixotropy Measured?
Measuring thixotropic behavior involves rheological testing to track how a material responds to shear stress and how quickly it recovers over time.
Stepped Shear Rate Tests
In these tests, a material is exposed to alternating high and low shear rates while viscosity is recorded. By plotting the shear stress during both the increasing and decreasing phases, a hysteresis loop is created.
The size of this loop reflects the energy needed to break down and rebuild the material’s internal structure, a key indicator of thixotropic strength. These tests are typically carried out using rotational rheometers, which provide detailed data on viscosity decay and recovery under controlled conditions.5
Thixotropy Loop
A thixotropy loop test simulates real-world processes like pumping or injection. The material is subjected to a controlled cycle: from low to high shear and then back to low. The loop’s enclosed area represents the extent of structural breakdown and recovery—the larger the area, the stronger the thixotropic response.
For instance, cement-struvite composites developed for 3D printing showed loop areas 3.6 times larger than conventional pastes, helping ensure the material held its shape after extrusion. Modern rheometers automate this process and often include temperature control to replicate manufacturing environments.10
Shear Recovery Tests
Shear recovery tests focus on how quickly a material regains its original viscosity after stress is removed. This is a key metric for evaluating stability in coatings, slurries, or suspensions.
Researchers monitor viscosity rebound over time, often using time-sweep oscillatory modes on a rheometer. For example, semi-solid magnesium alloys typically recover most of their viscosity within 5–10 minutes, making them ideal for complex aerospace applications requiring thixomolding.7
Why Thixotropy Matters Moving Forward
Thixotropy may not be a widely discussed material property, but its role in modern manufacturing is both versatile and essential. From improving flow control in metal injection molding to enabling sustainable, near-net-shape production, thixotropic behavior allows materials to be shaped and applied with greater precision and efficiency.
As the industry moves toward greener, smarter processes, a deeper understanding of thixotropy will be key, not only for improving performance but also for meeting evolving design, sustainability, and process reliability goals.
Want to stay ahead of the curve?
Sign up for our Rheology & Viscometry newsletter for insights on thixotropic materials, flow behavior, testing methods, and innovations in material design.
References and Further Reading
- Fei, Y. et al. (2022). From semisolid metal processing to thixotropic 3D printing of metallic alloys. Virtual and Physical Prototyping, 17(3), 489–507. DOI:10.1080/17452759.2022.2045674. https://www.tandfonline.com/doi/full/10.1080/17452759.2022.2045674
- How Thixomolding is Redefining Electric Vehicle Production - Light Metal Age Magazine. Light Metal Age Magazine. https://www.lightmetalage.com/news/industry-news/magnesium/how-thixomolding-is-redefining-electric-vehicle-production/
- Stirring Metals. Ingenia. https://www.ingenia.org.uk/articles/stirring-metals/
- Wang, Y., & Ewoldt, R. H. (2023). Thixotropy, antithixotropy, and viscoelasticity in hysteresis. Journal of Rheology, 67(6), 1199–1219. DOI:10.1122/8.0000620. https://pubs.aip.org/sor/jor/article-abstract/67/6/1199/2919146/Thixotropy-antithixotropy-and-viscoelasticity-in
- Azzi, L., & Ajersch, F. (2006). Analytical modeling of the rheological behavior of semisolid metals and composites. Metall Mater Trans B 37, 1067–1074. DOI:10.1007/BF02735029. https://link.springer.com/article/10.1007/BF02735029
- Shitole, S. et al. (2021). Review on the Current Progress of Thixoforming Process. DOI:10.1115/PVP2021-62263. https://asmedigitalcollection.asme.org/PVP/proceedings/PVP2021/85345/V004T06A015/1122148
- Huang, M. et al. (2024). Integrated manufacturing of powder metallurgy preparation-thixoforming for Al0.8Co0.5Cr1.5CuFeNi HEA: Excellent formability and enhancement by in-situ generated Al2O3 in liquid phase. Materials Science and Engineering: A, 916, 147289. DOI:10.1016/j.msea.2024.147289. https://www.sciencedirect.com/science/article/pii/S0921509324012206
- Dada, M. et al. (2019). High Entropy Alloys for Aerospace Applications. In Aerodynamics. DOI:10.5772/intechopen.84982. https://www.intechopen.com/chapters/66116
- What is thixotropy and how does it influence the manufacturing process? Oliver + Batlle. https://oliverbatlle.com/en/what-is-thixotropy/
- Ewuzie, U. et al. (2025). Investigating the thixotropy of fresh struvite cement-based composite: insights on mechanisms of the pastes’ thixotropic behavior. Cement and Concrete Composites, 106058. DOI:10.1016/j.cemconcomp.2025.106058. https://scholarsmine.mst.edu/che_bioeng_facwork/1970/
Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.