A disordered alloy does not have long range order but only has short range order. Due to the absence of long range order,  mobility of charge carriers decreases by several orders of magnitude as compared to their crystalline counterpart. This makes the conductivity very low in disordered alloys. Low conductivity means high resistivity in these alloys. Since short range order is not much different, the band gap does not change drastically in disordered alloys as compared to their crystalline counterpart. Slightly higher band gap in disorders alloys may also increase resistivity but the mobility effect is more pronounced in the increase in resistivity.

A disordered alloy does not have long range order but only has short range order. Due to the absence of long range order,  mobility of charge carriers decreases by several orders of magnitude as compared to their crystalline counterpart. This makes the conductivity very low in disordered alloys. Low conductivity means high resistivity in these alloys. Since short range order is not much different, the band gap does not change drastically in disordered alloys as compared to their crystalline counterpart. Slightly higher band gap in disorders alloys may also increase resistivity but the mobility effect is more pronounced in the increase in resistivity.

Current in the form of electrons flows from one complete atom to the next in metallic bonds quite readily. Valences, orientation and alignment of atoms follow a specific structure - hence "ordered" when crystalized in a regular pattern. as in an intermetallic mineral. When this is absent and the arrangement of the same metals in an alloy are not "ordered then the flow of electrons is hindered. The more the flow is hindered the higher the resistivity.

conductivity in polycrystalline is low.

disorder grains promotes disorientation of focaults currents

This increases its resistance

This high resistivity also increases the strength of the material over proportional in several alloying systems.

Dear Ahmed,

I apologize but I have not well understood your question.

Usually a disordered alloy is also crystalline. Or in this case, are you talking about the equivalent amorphous alloy?

In case the disordered alloy would be polycrystalline, I wonder if you are comparing it with the equivalent single crystal?

Could you be more precise with these points in your question?, in order we may try to help you.

Thanks

I am very pleased to thank you and I hope to be in good health and spend happy times

All greetings for you  all

God bless you,

First we should know what is order and disorder in alloys. If an alloy is made of two metals, say A and B, and if the concentration of B is small as compared to A, in the crystal of A, the atoms of B will be replaced according to the concentration of B.If that is true in whole of the sample of an alloy, we call it a solid solution or a disordered alloy.If on the other hand, the atoms of B are not randomly distributed in the matrix of B, we say that some sort of ordering is there in the alloy. 

In any case, the resistivity of alloy has a higher value than the resistivity of metal A because of disorder created in the matrix of metal A due to the presence of atoms of type B.