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Asked: 2020-04-19T07:02:26+05:30 In:

BARC-9: Why Pure Metals solidfy at a fixed temperature while Alloys solidfy over a range of temperatures?

BARC-9: Why Pure Metals solidfy at a fixed temperature while Alloys solidfy over a range of temperatures?
BARC-9: Why Pure Metals solidfy at a fixed temperature while Alloys solidfy over a range of temperatures?
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    10 Answers

    1. Silver

      F=C-P+1 at constant pressure At melting point, C=1,P=2 (liquid and solid), so for pure metals: F(degrees of freedom)=0, melting/freezing reaction is invariant and happens at a fixed temperature. Whereas, for alloys we have a composition variable.  For alloys: At melting point: C=2,P=2, So F=1 (univaRead more

      F=C-P+1 at constant pressure

      At melting point,

      C=1,P=2 (liquid and solid), so for pure metals: F(degrees of freedom)=0, melting/freezing reaction is invariant and happens at a fixed temperature. Whereas, for alloys we have a composition variable. 

      For alloys:

      At melting point:

      C=2,P=2, So F=1 (univariant reaction), that means either we can vary the temperature or composition as a variable. Melting/freezing does not takes place at a fixed temperature.

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    2. Silver Metallurgical Engineering student

      Pure metal is consists of same atomic bonds so it has single melting/solidification temperature. Alloy is a mixture so it consists of different bond. So temperature of melting/solidification is based on the composition of alloy.

      Pure metal is consists of same atomic bonds so it has single melting/solidification temperature.

      Alloy is a mixture so it consists of different bond. So temperature of melting/solidification is based on the composition of alloy.

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    3. Iron

      The melting point of a metal is related to the interatomic forces in the metal .when an alloy is formed the melting point is changed as the atoms now experience different interactions. Pure metals have a sharp and clear melting point .Being a mixture , alloys do not have fixed melting point . The meRead more

      The melting point of a metal is related to the interatomic forces in the metal .when an alloy is formed the melting point is changed as the atoms now experience different interactions.

      Pure metals have a sharp and clear melting point .Being a mixture , alloys do not have fixed melting point . The melting point depends upon the concentration of the metals and the impurities present

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    4. Copper Student

      The pure metal liquid is freezing point the solidification starts the evoluation of Latent heat.The heat evolved compensates lost of heat to the surroundings..Still the temperature remains constant up to completion of solidification

      The pure metal liquid is freezing point the solidification starts the evoluation of Latent heat.The heat evolved compensates lost of heat to the surroundings..Still the temperature remains constant up to completion of solidification

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    5. Copper

      Pure metal solidifies at fixed temperature because it has the constituents of the very parent metal and no other matal is dissolved or added to it making it an alloy, so it consists same type of bonding. Whereas alloy consists mixture of two or more metals. So it consists different type of bonds. ThRead more

      Pure metal solidifies at fixed temperature because it has the constituents of the very parent metal and no other matal is dissolved or added to it making it an alloy, so it consists same type of bonding. Whereas alloy consists mixture of two or more metals. So it consists different type of bonds. That’s why can’t be solified at fixed temperature.

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    6. Gold B.TECH, NIT DURGAPUR

      Pure metal solidify at fixed temperature as it has identical bond energy While alloys solidify over a range of temperatures because in case of alloy it don't have identical surrounding meaning they don't have identical bond energy,thus different bond break at different temperature

      Pure metal solidify at fixed temperature as it has identical bond energy

      While alloys solidify over a range of temperatures because in case of alloy it don’t have identical surrounding meaning they don’t have identical bond energy,thus different bond break at different temperature

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    7. Platinum

      A pure metal consists of same kind of atomic bonds. So all the bonds can break at a single temp or we can say  it is solidified at a single temperature. But an alloy is a mixture of two or more metals. So it has different kind of bonds. So all the bonds can not break at a single temp. They are solidRead more

      A pure metal consists of same kind of atomic bonds. So all the bonds can break at a single temp or we can say  it is solidified at a single temperature. But an alloy is a mixture of two or more metals. So it has different kind of bonds. So all the bonds can not break at a single temp. They are solidified at range of temperatures.

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      • Copper

        If different bonding is only the reason for range of melting temperature in the alloy , even in some metals apart from metallic bonding some percentage of other type of bonding is present then it should also melt at range of temperature ? Furthermore, eutectic alloy should melt at different range ofRead more

        If different bonding is only the reason for range of melting temperature in the alloy , even in some metals apart from metallic bonding some percentage of other type of bonding is present then it should also melt at range of temperature ?

        Furthermore, eutectic alloy should melt at different range of temperature according to you but it has fixed melting temperature ?

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        • In a pure metal A all bonds are A----A type. These bond have a Sharpe energy cutoff above which it will break. The temperature at which this energy requirement is meet is called melting point. In alloys A-B there are A----A , A-----B, B------B type bonds, all three bonds have different energy cutoffRead more

          In a pure metal A all bonds are A—-A type. These bond have a Sharpe energy cutoff above which it will break. The temperature at which this energy requirement is meet is called melting point.

          In alloys A-B there are A—-A , A—–B, B——B type bonds, all three bonds have different energy cutoff for breaking. so as we heat the alloys different bond break at different temperature and we get range of melting (starting of bond breaking to finishing of bond breaking) not the single point.

          the eutectic point is balance between the number type of A—-A , A—–B, B——B bonds such as way that it act as single point energy all the atoms will break.

           

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    8. Pure metals having a standard atomic bonding it's melt at definite temperature , but alloys are mixture of metalls&alloys so they are defferent atomic bonding  so it's at melt at high temperature

      Pure metals having a standard atomic bonding it’s melt at definite temperature , but alloys are mixture of metalls&alloys so they are defferent atomic bonding  so it’s at melt at high temperature

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    9. Alloys contains elements with varying melting point and have different thermodynamic properties. the uniformity of properties is lost in alloys whereas it is retained well in pure metals. so pure metals solids at fixed temp while alloys over a range. so alloys

      Alloys contains elements with varying melting point and have different thermodynamic properties.
      the uniformity of properties is lost in alloys whereas it is retained well in pure metals.
      so pure metals solids at fixed temp while alloys over a range.
      so alloys

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    10. Gold Metallurgist, Standard Provider (IS, ASTM, BS, ISO etc), Laboratory Equipment Suppliers,

      In the case of castings, after pouring of the molten metal in the mould, the temperature falls steadily until freezing commences at a particular point. During solidification, the temperature more or less remains constant due to release of latent heat. Actually, there may be a slight increase in tempRead more

      In the case of castings, after pouring of the molten metal in the mould, the temperature falls steadily until freezing commences at a particular point. During solidification, the temperature more or less remains constant due to release of latent heat. Actually, there may be a slight increase in temperature if super cooling has occurred (Refer Fig. 3.36).

      The temperature again starts falling steadily in case of pure metal. In the case of alloy, commencement of crystallisation is followed by a period of less steep temperature reduction while the metal is passing through the mushy state [Refer Fig. 3.36 (b)].

      Since an alloy does not have a sharply defined freezing temperature, solidification takes place over a range of temperature. The solids separating out at different temperatures, therefore, possess different compositions.

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