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Comments on “elastic moduli of Cu Ni, Au Ag and Cu Zn solid solutions”
289
Materials Science and Engineering, 18 (1975) 289 © Elsevier Sequoia S.A., Lausanne -- Printed in The Netherlands
Letter to the Editor
Comments on "Elastic moduli of Cu - Ni, Au - Ag and Cu - Zn solid solutions"
W. KOSTER
Max-Planck-Institute fiir MetaUforschung, 7000 Stuttgart 1, Seestrasse 75 (W. Germany) (Received August 29, 1974)
Subrahmanyam [1] has published three series of data on the behavior of the modulus of elasticity of polycrystalline alloys in solid solutions. His statements should be criticized. 1. T h e a solid solution o f c o p p e r with zinc
By adding zinc the modulus of elasticity of copper is initially increased [2,3]. This fact has been unanimously observed by all authors who have carried out measurements on this system. The subsequent linear decrease in the modulus does not start from the modulus value of copper (~ 12,500 kp/mm 2), but rather from a fictitious value of about 13,300 kp/mm 2. 2. The gold - silver solid solution
According to Subrahmanyam [1] the value of the modulus of elasticity changes linearly from the value of gold to that of silver. According to other measurements [3,4] the values lie on a curve slightly convexed towards higher values. This curve shape is maintained up to 700°C. 3. T h e c o p p e r - nickel solid solution
Subrahmanyam [ 1 ] gives a linear course from the value of the copper modulus to that
of ferromagnetic nickel in demagnetized state (~ 19,600 kp/mm2). In reality the curve runs from the above-mentioned fictitious copper value linearly to the value of magnetically saturated nickel (~ 22,300 kp/mm 2) [2,3 ]. The AE-effect in the ferromagnetic range of the copper - nickel series of alloys has been ignored. The author's conclusion from the few tests he carried out, namely, that the modulus of elasticity changes in uninterrupted solid solutions always linearly with the concentration, is incorrect. It can change according to the rule of mixtures but can also lie on curves bent towards slightly lower values (Co - Pt) or bent towards slightly higher values (Ag- Pd), Au- Pd).
REFERENCES 1 B. Subrahmanyarn, Mater. Sci. Eng., 15 (1974) 177. 2 Z. Nishiyama, Sci. Rept. TShoku Univ., 18 (1929) 359. 3 W. KSster and W. Rauscher, Z. Metallk., 39 (1948) 111. 4 A. RShl, Ann. Physik, (5) 16 (1933) 887. 5 E.Gri):eisen, Ann. Physik, (4) 22 (1907) 801.
Materials Science and Engineering, 18 (1975) 289 © Elsevier Sequoia S.A., Lausanne -- Printed in The Netherlands
Letter to the Editor
Comments on "Elastic moduli of Cu - Ni, Au - Ag and Cu - Zn solid solutions"
W. KOSTER
Max-Planck-Institute fiir MetaUforschung, 7000 Stuttgart 1, Seestrasse 75 (W. Germany) (Received August 29, 1974)
Subrahmanyam [1] has published three series of data on the behavior of the modulus of elasticity of polycrystalline alloys in solid solutions. His statements should be criticized. 1. T h e a solid solution o f c o p p e r with zinc
By adding zinc the modulus of elasticity of copper is initially increased [2,3]. This fact has been unanimously observed by all authors who have carried out measurements on this system. The subsequent linear decrease in the modulus does not start from the modulus value of copper (~ 12,500 kp/mm 2), but rather from a fictitious value of about 13,300 kp/mm 2. 2. The gold - silver solid solution
According to Subrahmanyam [1] the value of the modulus of elasticity changes linearly from the value of gold to that of silver. According to other measurements [3,4] the values lie on a curve slightly convexed towards higher values. This curve shape is maintained up to 700°C. 3. T h e c o p p e r - nickel solid solution
Subrahmanyam [ 1 ] gives a linear course from the value of the copper modulus to that
of ferromagnetic nickel in demagnetized state (~ 19,600 kp/mm2). In reality the curve runs from the above-mentioned fictitious copper value linearly to the value of magnetically saturated nickel (~ 22,300 kp/mm 2) [2,3 ]. The AE-effect in the ferromagnetic range of the copper - nickel series of alloys has been ignored. The author's conclusion from the few tests he carried out, namely, that the modulus of elasticity changes in uninterrupted solid solutions always linearly with the concentration, is incorrect. It can change according to the rule of mixtures but can also lie on curves bent towards slightly lower values (Co - Pt) or bent towards slightly higher values (Ag- Pd), Au- Pd).
REFERENCES 1 B. Subrahmanyarn, Mater. Sci. Eng., 15 (1974) 177. 2 Z. Nishiyama, Sci. Rept. TShoku Univ., 18 (1929) 359. 3 W. KSster and W. Rauscher, Z. Metallk., 39 (1948) 111. 4 A. RShl, Ann. Physik, (5) 16 (1933) 887. 5 E.Gri):eisen, Ann. Physik, (4) 22 (1907) 801.