Tin-Lead Alloy System’s Binary Phase Diagram

Binary phase diagrams of specific alloy systems, show information about alloy systems in which metallurgists can make very good assessments. Also, binary systems are very important in engineering that constitute very important engineering materials. Tin-lead alloys are also a very important non-ferrous binary alloy system in metallurgy. In this article, we will explain the tin-lead alloy system with its binary phase diagram below.

Fundamentals of Modern Manufacturing: Materials, Processes, and Systems

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What Are The Properties Of The Tin-Lead Alloy System?

Binary phase diagram of Tin-Lead alloy system.

As you see above binary diagram of the Tin-Lead system. There are various kinds of phases are available in various compositions of tin. The vertical axes are showing the temperature values, the left side is showing the Celsius, the right side is showing the Fahrenheit. The lines inside the diagram are showing the boundaries of various phases of the Tin-Lead alloy system.

There are two solid phases in the Tin-Lead alloy system that can be seen on the left and right sides of the diagram. The right side solid phase is called as alpha phase and the left side solid phase is called the beta phase in the Sn-Pb alloy system. Upon the upside lines of these solid phases, the alloy system turns into a solid+liquid phase. If we take a look at the melting points of pure compositions of Sn and Pb, the melting line of the changing compositions meet at one point that is called ‘eutectic composition’ which includes 61.9% of Sn. The temperature of that eutectic point is 183 Celsius. As you can see above, the eutectic composition of Sn-Pb alloy has the lowest melting temperature compared with other composition percents.

The composition of the eutectic phase pf Sn-Pb alloy can be turned into liquid directly from the solid phase, without going through the solid+liquid phase.

Sn-Pb alloys are generally used in electrical and electronic components in today’s technology.


The assessment of Sn-Pb binary phase diagram is very easy like above. Do not forget to leave your comments and questions about ‘Sn-Pb binary phase diagrams’ below!

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