You will probably struggle to differentiate between the ferrite and the martensite fractions by XRD. The key thing you have not mentioned is the carbon content of your alloy, i.e. low, medium or high. If the carbon content is low, then the martensite unit cell wil be more or less similar to that of the ferrite, i.e. ~ BCC. As the carbon level increases then the martensite unit cell gradually changes from BCC to BCT, i.e. body centred tetragonal, with its C to A ratio being a function of the carbon content. You will start to pick this up in the XRD traces.

However, if you get a good etching response, I would go with the suggestion of Ryzhkov and use a point counting method. If you don't have a machine for this, e.g. Swift Point Counter, then make yourself a grid on an acetete sheet, and overlay lay this on to a digital image of the steel's microstructure. Count the intersections that are in ferrite and those in martensite.

You should read a couple of primers on the errors and practical considerations before embarking on such work, as a starter I recommend, 'The Basis of Quantitative Metallography'  by F.B. Pickering, Monograph no.1 published by the Institute of Metallurgists (now IMMM), and 'Worked Examples in Quantitative Metallography' by R. Higginson and C.M. Sellars.

By doing this you will be able to quote error limits on your measured values. There are international standards for such procedures.

ISO 9042:1988

Steels -- Manual point counting method for statistically estimating the volume fraction of a constituent with a point grid

Follow this if you wish to provide results to a third party, rather than for your own consumption, e.g. you may just be wanting a ballpark estimate for your own use.

thank you sir.,

For calculation a percentage of each phase from the XRD pattern you can refer to this paper "Structure and magnetic properties of Ni0.64Zn0.36Fe2O4

nanoparticles synthesized by high-energy milling and subsequent

heat treatment" J Mater Sci: Mater Electron

DOI 10.1007/s10854-014-2597-4. By A. Hajalilou

As far as I know, it is possible to calculate volume fractions of ferrite and martensite in medium carbon low alloy steel using optical metallography and, say, point count method or method of three circles in case image analyser is not available. Named microstructures are clearly defined after nital (4 % HNO3 in C2H5OH) etching. Anyway, for XRD measurements you need to prepare a polished surface on the sample. Try to etch it and examine using simple metallographic microscope.

You will probably struggle to differentiate between the ferrite and the martensite fractions by XRD. The key thing you have not mentioned is the carbon content of your alloy, i.e. low, medium or high. If the carbon content is low, then the martensite unit cell wil be more or less similar to that of the ferrite, i.e. ~ BCC. As the carbon level increases then the martensite unit cell gradually changes from BCC to BCT, i.e. body centred tetragonal, with its C to A ratio being a function of the carbon content. You will start to pick this up in the XRD traces.

However, if you get a good etching response, I would go with the suggestion of Ryzhkov and use a point counting method. If you don't have a machine for this, e.g. Swift Point Counter, then make yourself a grid on an acetete sheet, and overlay lay this on to a digital image of the steel's microstructure. Count the intersections that are in ferrite and those in martensite.

You should read a couple of primers on the errors and practical considerations before embarking on such work, as a starter I recommend, 'The Basis of Quantitative Metallography'  by F.B. Pickering, Monograph no.1 published by the Institute of Metallurgists (now IMMM), and 'Worked Examples in Quantitative Metallography' by R. Higginson and C.M. Sellars.

By doing this you will be able to quote error limits on your measured values. There are international standards for such procedures.

ISO 9042:1988

Steels -- Manual point counting method for statistically estimating the volume fraction of a constituent with a point grid

Follow this if you wish to provide results to a third party, rather than for your own consumption, e.g. you may just be wanting a ballpark estimate for your own use.

Dear S. Prabhakaran

"Can anyone tell me, how can I calculate the volume fraction of ferrite and martensite in medium carbon low alloy steel? Is it possible via XRD?"

1. The well known textbooks on XRD  of Cullity and Klug/Alexander provide information on XRD-procedures for phase analysis. It shoud be noted that the XRD-phase analysis presumes that the specimens studied can be conceived as powder samples, i.e. without noticeable texture.

2. The remarks of Ryzhkov and Butler hint at quantitative microscopy. Here it is noted that the cross-sections studied at an appropiate magnification should together be representive for the specimen itself whereas the specimen should be representive for the quenched condition of the low alloy steel studied.

3. As mr Butler pointed out, the carbon content of the low alloy steel is of predominant importance. For high carbon contents, residual austenite may enter into consideration.

As suggested by  Ryzhkov, I feel optical metallography followed by image analysis is the best way to identify different volume fraction of ferrite and martensite. This can be rechecked by magnetic saturation magnetisation measurement as the saturation magnetisation of ferrite and martensite are different.

Thank you all for your great suggestions. 

you can get the volume fraction by optical image analyser

thank you Mahesh Davanageri sir..,