Abstract
The tests were carried out in order to explain the variation of crystal lattice strain in various graphites by heat-treatment . The flake, spheroidal and temper graphites are prepared from gray, calcium ductile and black heart malleable cast irons by electrolytic extraction. The specimens are heat-treated under argon or vacuum at 1200°C, 1500°C, 1800°C, 2000°C, 2400°C, 2600°C and 3050°C, respectively . The crystal lattice strain in graphites is analyzed from the equation as follow,
β (obs) ·cosθ=η·sinθ+K·λ/D (hkl)
Where β (obs) is the half maximum line breadth, θ the scattering angle, η the parameter of lattice strain (Δd/d), K the shape factor, λ the wavelength and D (hkl) the crystallite size. The relation between β (obs) ·cosθ and sinθ obtained from (00l) lines is comparatively linear. As result, the variation of lattice strain with heat treatment is the largest in temper graphite, slightly smaller in spheroidal graphite and almost nothing in flake graphite.
