Strength of iron under pressure up to 55 GPa from X-ray diffraction line-width analysis13;

The X-ray diffraction patterns are recorded from polycrystalline iron sample compressed in a diamond anvil cell up to 55 GPa. The maximum micro-stress in the sample, a measure of compressive strength, is derived from the line-width analysis. The strength of iron in the body centered cubic (BCC)-phase is 1.1amp;plusmn;0.2 GPa. This value is in good agreement with the strength derived from the hardness vs. grain-size data. The strength increases steeply during the BCC-hexagonal closed packed (HCP) transition. The strength-pressure data for HCP-iron fit the relation amp;sigma; = 2.9 + 0.028 P, where amp;sigma; and P are the compressive strength and pressure in GPa, respectively. The present results agree well with those obtained from the line shift analysis carried out in earlier studies