Temperature dependence of mechanical properties of boron fibers
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Within the 293–873°K temperature range both bare and SiC-coated boron fibers deform elastically while retaining their rather excellent strength characteristics.
Residual elongation appears within the 873–973°K temperature range and reaches its maximum at 1073°K. Gradual enbrittlement of the material at further rising temperature is due to corrosion and structural change.
An analysis of changes in the ultimate strength and in the defects initiating fracture of fibers with rising temperature has revealed that the temperature dependence of the strength is determined essentially by the redistribution of internal stresses within the 293–873°K range and by corrosion, as well as by structural changes in boron fibers within the 873–1473°K range.
The modulus of elasticity of tested fibers decreases with rising temperature, almost linearly, over the 293–1473°K range. Empirical relations have been obtained for the temperature dependence of the modulus of elasticity.
KeywordsMechanical Property Boron Structural Change Internal Stress Ultimate Strength
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