Portal de Periódicos da CAPES

The Temperature Dependence of Work-Hardening due to Orowan Loops in a Dispersion-Hardened Alloy

1979; Japan Institute of Metals and Materials; Volume: 20; Issue: 7 Linguagem: Inglês

10.2320/matertrans1960.20.395

2432-4701

Keisuke Matsuura,

High Temperature Alloys and Creep

The temperature dependence of work-hardening of dispersion-hardened alloy, which is due to Orowan loops formed around dispersed particles, has been calculated on the basis of a model that Orowan loops climb and disappear through a pipe diffusion of vacancies along the loops during the deformation. Assuming a uniform distribution of Orowan loops around each particle, the rate of their disappearance was obtained by considering the total vacancy flux in a whole distribution of loops, and the amount and rate of work-hardening were finally given as a function of deformation temperature and particle size. Furthermore, these expressions were extended to the case in which there was a distribution of particle size.The calculation explains well an outline of the temperature and particle size dependence of work-hardening rate in an Al-1.2% Si alloy containing silicon particles, if reasonable values are used as the diffusion coefficient for pipe diffusion, that is D0p=10−3 cm2/s; Qp=58.6 kJ/(mol K) and D0p=10−2 cm2/s; Qp=66.9 kJ/(mol K), where D0p and Qp mean a frequency factor and an activation energy for pipe diffusion respectively. However, the calculated work-hardening rate decreased more rapidly with increasing deformation temperature in a narrower temperature range than the measured one for the Al-1.2% Si alloy. This discrepancy has been discussed and ascribed to the fact that the rate of climb of the Orowan loop depends on the position it lies on the particle interface, while it is not considered in the present calculation.