Metallurgy; an introduction to the study of physical metallurgy . lex,but consists of primary crystals of either antimony or of theantimony-tin compound, embedded in two layers of the case of white bearing-metals the requirements are diffe-rent—^what is wanted is a metal sufficiently soft and plastic toaccomodate itself to the ineqiiahties of the moving parts andthus to afford them an even bearing, while it must also present 136 STUDY OF PHYSICAL METALLURGY a surface of suflBicient hardness to prevent rapid crystals of the tin-antimony compound serve to providethe resi
Metallurgy; an introduction to the study of physical metallurgy . lex,but consists of primary crystals of either antimony or of theantimony-tin compound, embedded in two layers of the case of white bearing-metals the requirements are diffe-rent—^what is wanted is a metal sufficiently soft and plastic toaccomodate itself to the ineqiiahties of the moving parts andthus to afford them an even bearing, while it must also present 136 STUDY OF PHYSICAL METALLURGY a surface of suflBicient hardness to prevent rapid crystals of the tin-antimony compound serve to providethe resisting hard surface, while the soft and plastic eutecticsin which they are embedded yield to the pressure and adaptthemselves to the needs of the bearing in question. The typicalstructure of an alloy consisting of the hard crystals of SbSnembedded in eutectic is shown in Fig. 47, Plate IX. We now pass on to consider the constitutional diagram andthe correlated micro-structures of a decidedly more complexsystem of alloys, viz., those of aluminium and zinc. This. toot 70 80 0 10 20 30 40 SO 60Zn Composition. FiQ. 48.—Constitutioaal Diagram of the Zinc-Alumiixiuin Alloys, SO system stiU shows a well-defined eutectic, but at the one endof the series there is a long range of sohd solutions, while theseries also shows one definite compound possessing somewhatremarkable features. This series is of interest as forming thebasis of what are probably the best available Hght alloys ofaluminium, some of which combine a comparatively lowdensity (about 325) with the strength and toughness of mildsteel. The constitutional diagram is shown in Fig. 48. In thiscase also a much simpler diagram was for a long time generallyaccepted; the author and Archbutt {*), however, estabhshedthe diagram here shown which is itself not quite complete in TYPICAL ALLOY SYSTEMS 137 regard to the region occupied by the dotted continuations ofthe lines CGH and IJKL. The diagram consists first of allof the f
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectmetals, bookyear1922
