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In my physics textbook, they have written that metals in general have a higher Young's modulus when compared to alloys. On the contrary, in the same chapter they have mentioned that steel has a higher Young's modulus than copper, aluminium etc. Is there any generality that can be made here? Here, they say that steel is more elastic and have provided some data in the table which helps their point.

Here they have mentioned how metals have higher elasticity than alloys and elastomers.

Ref: NCERT Physics Textbook Part 1, Class XI; Chapter- Mechanical Properties of Solids.

Aayush Jha
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    The only generality is that your physics textbook sucks, if it believes that alloys are not metal. Are you sure it does not refer to "pure metal", which is a completely different thing from just "metal" – PcMan May 06 '21 at 10:44
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    Note that the Young's Modulus of materials such as steel doeneds highly on the processing of the material and not just on the material type. There is enormous difference in elasticity and hardness for e.g. cold-worked or cast steel. – Steeven May 06 '21 at 12:36
  • https://physics.stackexchange.com/questions/395105/why-doesnt-the-youngs-modulus-change-when-an-alloy-is-strengthened has some useful info. Further, there are certainly binary phases with higher Young's modulus than either pure element. I think the physics textbook is quite incorrect in general. – Jon Custer May 06 '21 at 13:54
  • Please post the name of the textbook and the exact text. – Chemomechanics May 06 '21 at 14:37
  • I have just added the pictures and the source. Please take a look. Thanks – Aayush Jha May 06 '21 at 15:15

1 Answers1

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Unfortunately, you have a bad textbook. Try to find others to supplement it. Here are some problems.

  • Most importantly to your question, alloys generally refers to metals. Thus, "Metals have larger values of Young's modulus than alloys" is near meaningless. Perhaps the authors mean "pure metals," but this too is incorrect. Many alloys are stiffer than many pure metals.

  • "More elastic" is ambiguous, and the insistence that the meaning is always "stiffer" does not reflect any consensus in the field.

  • Nobody refers to aortic tissue as an elastomer, as a look at the literature reveals. Elastomer generally refers to a synthetic substance; tissue is a biological substance.

  • Stress can certainly be assigned an orientation, as in the components of the rank-two stress tensor. Perhaps the authors mean "pressure," but this doesn't match the context of axial stress that's being discussed.

  • The language is generally poor, with missing articles and other grammatical and formatting problems; this suggests that the content hasn't received careful review.

Again, I wouldn't consider this resource to be a reliable one.

Chemomechanics
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  • Thanks a lot for the clarification. This is actually the 'prescribed textbook' , and I am reading this for the first time since a lot of questions directly come from in between the lines in our pre-med entrance test. Will read the same topic in some other book. Cheers. – Aayush Jha May 07 '21 at 01:08