Cu-Zn System Research Articles

Heat Capacity ofα-CuZn Alloys below 4.2°K

Low-temperature heat capacity measurements have been made on a series of high-purity specimens covering the entire $\ensuremath{\gamma}$ phase of the Cu-Zn system. The electronic heat capacity decreases rapidly with increasing zinc concentration, thereby lending support to the hypothesis that the $\ensuremath{\gamma}$ brasses are electron compounds. An excellent fit to the data may be obtained by assuming that the Fermi surface of these alloys is spherical and makes contact with the large Brillouin zone of the $\ensuremath{\gamma}$-brass structure. The Debye temperature of the alloys is 433\ifmmode^\circ\else\textdegree\fi{}K and is approximately independent of zinc concentration.

硬ロウ材の高温機械的性質について

In using the brazed joint at high temperature, we have thought that the strength of brazed joints is related to the mechanical properties of brazing filler alloys at elevated temperatures. In this study, we adopted nine kinds of brazing filler alloy composed of Ag-P-Cu, Ag-Cu-Zn-Cd and Cu-Zn systems that were used for brazing copper and copper alloys, and tested their tensile strength, elongation and hardness in the range from the room temperature to 500°C.The test results are summarized as follows;1) Ag-P-Cu systemsWith an increasing content of Ag, the mechanical properties at the room and elevated temperatures improved, and a filler alloy of 5%Ag is stronger than one of 15%Ag at the temperature under 250°C, but at over 250°C, the opposite is true.2) Ag-Cu-Zu-Cd systems No definite relationship was found between Ag content and mechanical properties at elevated temperatures.3) The mechanical properties of Ag-P-Cu systems are stronger than those of Ag-Cu-Zu-Cd systems at the temperature under 250°C but at over 250°C, the opposste is true.4) The influences of work hardening on the strength of Ag-P-Cu systems are eliminated at 250°C, but on that of Ag-Cu-Zn-Cd systems they remain a little at 500°C.The mechanical properties at elevated temperatures have been improved by work hardening and the effect of the latter is remarkable with an increasing Ag content.

Effect of Stress on the Martensitic Transformation in the Cu-Zn System

Effect of Stress on the Martensitic Transformation in the Cu-Zn System

Mobilities in Diffusion in Alpha Brass

Diffusion coefficients and mobilities were determined as functions of concentration in the a phase of the Cu-Zn system. Use was made of incremental diffusion couples to determine the Kirkendall effect at various concentrations. Darken’s analysis was used to calculate the individual diffusion coefficients and mobilities from these data. The general diffusion coefficient is a single-valued function of the concentration in this system to within the limits of accuracy of the experimental methods used. The form of the various functions (diffusion coefficients and mobilities) of concentration is the same in every case: it is essentially the same as the usual D vs c curve.

合金の腐蝕に関する基礎的研究（第4報）Cu-Zn系の腐蝕度とε相の異常性（その1）

合金の腐蝕に関する基礎的研究（第4報）Cu-Zn系の腐蝕度とε相の異常性（その1）

冷間加工せる金屬及び合金の低温燒鈍による諸性質の變化に就て

In a previous work, (1) the author studied the so called “Strain Aging” phenomenon of some alloys and proved that in u brass and a Al-bronze, the increase of electric resistance produced by cold work is very great and the hardening phenomenon takes place corresponding to the 1 st. decrease of electric resistance in annealing process. In order to reveal the mechanism of hardening and to study the existence of analogous phenomenon, the author made a further reserch on the annealing characteristics of cold drawn Cu-Ni, Cu-Si, Cu-Sn, Cu-Be, Cu-Mn, Ag-Cd, Ag-Zn, Ag-Sn, Al-Zn, Al-Mg alloys and pure Al, measuring electric resistance, tensile strength and hardness. For the alloys of Cu-Ni, Cu-Al, Cu-Zn systems in water quenched and annealed states, measurements of electric resistance were made at high temperature. The results obtained may be summarized as follows: (1) The increase of electric resistance of pure Al produced by cold work is very small and is recovered at the recrystallization temperature. (2) On annealing Al-Mg, Al-Zn, Cu-Si, Cu-Sn and Ag-Sn alloys the ordinary recovery process occured. (3) In Ag-Cd and Ag-Zn alloys, analogous to a brass and a Al-bronze, the percentage increase of electric resistance produced by cold work is very great and the hardening phenomenon takes place corresponding to the 1 st. decrease of electric resistance in annealing process. (4) On annealing Cu-Ni alloys of high Ni contents, the hardening phenomenon takes place. Aa a result of high temperature-electric resistance measurement, a kind of order-disorder transformation is found to take place in Cu-Ni system and it is presumed that the hardening phenomenon is due to this transformation. (5) The anomality, presumely analogous to the case of Cu-Ni system, is found to take place in Cu-Al system and Cu-Zn system by means of high temperature-electric resistance measurement. And the hardening phenomenon of a brass and a Al-bronze is presumed to be due to this anomality. (6) On studying the relation between the concentration of solid solution and the percentage increase of electric resistance produced by same degree of cold work, it is found that the marked discontinuous increase of electric resistance takes place from some atomic % of solute atoms in Cu-Al, Cu-Zn, Cu-Ni, Ag-Zn and Ag-Cd system. (7) The hardening phenomenon of cold worked Cu-Be alloy and Cu-Mn alloys of high Mn % by low temperature annealing is presumed to be due to the precipitation of γ phase and a Mn.

Orientation in Peritectic Structures

PRELIMINARY results from an X-ray study of the peritectic reaction + liquid in the Cu-Zn system prove that the orientations assumed by the -phase are definitely related to the orientation of the -phase. Specimens suitable for accurate orientation studies (by means of back-reflection Laue patterns) were prepared by solidifying a pure -alloy (52 per cent copper) under a uniform temperature gradient, and seeding the crystallisation with a copper single crystal. The resulting specimens then consist (in order, from bottom to top) of (a) copper crystal seed, (b) primary crystallised -phase having the same orientation as the copper seed, (c) large -grains (2–5 mm.), the nuclei of which originated in the peritectic reaction +liquid; these -grains have a narrow rim of segregated -phase. This sequence of crystallisation is made possible, as was expected, by the diffusion of copper into the liquid -brass adjacent to the solid copper crystal.

X-ray study of phase boundaries in thermal diagrams of alloy systems—cu-zn system

Within the last 10 years, the study of the diffraction of X-rays by crystal units in metals and alloys has shown that X-ray analysis, apart from giving data on the form and dimensions of the crystalline units, is a powerful method with which to examine the thermal diagrams of alloy systems. Rosenhain has pointed out, however, that although the X-ray analysis of alloys yields valuable results as to structure and so on, the constitutional diagrams arrived at by this means must necessarily be incomplete, firstly because a very small amount of a second phase in a large mass of another phase cannot be detected by X-ray methods, and secondly, because the parameter measurements have not been accurate enough to determine definitely the boundaries of solid solubility. In view of this statement we felt it would perhaps serve a useful purpose to carry out a careful investigation into the reliability of accurate X-ray methods for establishing thermal equilibrium diagrams of alloy systems. An account of such an investigation is given in this paper, and it may be stated at the outset that, where X-ray data could be compared with data reliably established by other methods, the agreement is as good as, if not better than, that between the data of the various methods amongst themselves. It will be shown that a phase boundary can be determined by the X-ray method from parameter measurements alone, and that an accurate determination can be made irrespective of the amount of the second phase present. It will be necessary to go into the method of measurement and the heat treatment of the alloys in some detail. Precautions have to be taken in the preparation and analysis of the alloys to ensure that the parameter measured is that of the alloy in the equilibrium state, and that its composition is that corresponding to the alloy actually used in the measurement. The paper is therefore divided into two parts; the first part deals with the method of measurement and the preparation of the alloys, and the second part refers to the X-ray examination of the alloys with a view to determining the phase boundaries.

The application of X-rays to the study of alloys

Since the middle of last century it has been known that the alloys, obtained by melting together two or more metals, are conglomerates of small crystals. As it is impossible to study them under the polarizing microscope because of their high absorbing power for light, and as they are seldom obtained in crystals with faces sufficiently well developed to allow a measurement of their angles, our crystallographic knowledge has been, until recently, extremely small. When, therefore, the X-ray methods came to the assistance of the metallurgist they were sure of a welcome. In 1922, Bain, using the powder-photograph method of Debye and Hull, carried out some very important pioneering work. In 1924, Owen and Preston, of the National Physical Laboratory, working in conjunction with Rosenhain studied the Cu-Al and Cu-Zn systems. They used a powder method with an ionization spectrometer. Their work marked a great advance, on account of the precision of their measurements and their detailed description of the preparation of the samples of alloys. At the same time Westgren and Phragmen, working in Stockholm with a photographic method, studied independently the same systems as Owen and Preston, and obtained results of equal precision. They extended the work in certain directions by making a more thorough investigation of single crystals. They have now undertaken an extensive research on several alloys and on steels.