Method of judging practical conditions for use of an ordered alloy under irradiation environments
View Patent ↗An irradiated state diagram that expresses a relation of a degree of long range order S to a variable R of an irradiated state related to a damage rate and an irradiation temperature is prepared according to an ordered structure of an alloy on basis of an evaluation formula related to an effect of irradiation on an irradiated state of the alloy by using, as parameters, a first threshold value S th1 at which the degree of long range order begins to decrease greatly under irradiation, a second threshold value S th2 at which the degree of long range order substantially reaches equilibrium after this decrease, and a degree of long range order in an equilibrium state S eq . An R-value is calculated and an S-value corresponding to the R-value is found. An S th1 -value, an S th2 -value and an S eq -value at the R-value are found and compared.
1. A method of judging practical conditions for use of an ordered structure alloy under an irradiation environment, comprising:
preparing an irradiated state diagram that expresses for the ordered structure alloy a relation of a degree of long range order S to a variable R of an irradiated state of the ordered structure alloy, related to a damage rate and an irradiation temperature, on basis of an evaluation formula related to an effect of irradiation on the degree of long range order of the ordered structure alloy under irradiation environments by using as parameters, a first threshold value S th1 at which the degree of long range order begins to decrease, under irradiation, at a rate greater than a rate at which the degree of long range order decreased prior to the first threshold value having been reached, a second threshold value S th2 at which the degree of long range order is nearer to reaching equilibrium than the degree of long range order was prior to the second threshold value having been reached and after decrease of the degree of the long range order which began at the first threshold value S th1 , and the degree of long range order in an equilibrium state S eq ;
for irradiation conditions under which the ordered structure alloy is to be used, calculating an R-value, and corresponding to the R-value, finding an S-value, an S th1 -value, an S th2 -value, and an S eq -value; and
comparing the S-value, the S th1 -value, the S th2 -value, and the S eq -value, to thereby predict a damage level and a variation condition of the damage level of the ordered structure alloy under the irradiation environment.
2. The method according to claim 1 , wherein
comparing the S-value, the S th1 -value, the S th2 -value, and the S eq -value, with 0<S eq -value<S th2 -value<S th1 -value<1, and considering a magnitude relation of these values, results in the following judgments being made
(i) when S th1 -value<S-value, the ordered structure alloy is in an ordered state and has a large degree of long range order, corresponding to a low damage level,
(ii) when S th2 -value<S-value<S th1 -value, the ordered structure alloy is in a transition process from an ordered state to a disordered state and the degree of long range order decreases, corresponding to a damage level of the alloy fluctuating greatly and tending to increase rapidly,
(iii) when S eq -value<S-value<S th2 -value, the ordered structure alloy is in a process of reaching a disordered state and an amount of a decrease in the degree of long range order is small while the degree of long range order is small, corresponding to a damage level of the alloy being large but fluctuating little, and
(iv) when S-value<S eq -value, the ordered structure alloy is in a disordered state and the degree of long range order is small, corresponding to a high damage level.
3. The method according to claim 2 , wherein
the degree of long range order S is equal to the probability that composed sublattices are correctly occupied by constituent atoms minus the probability that that composed sublattices are not correctly occupied by constituent atoms.
4. The method according to claim 1 , wherein
the degree of long range order S is equal to the probability that composed sublattices are correctly occupied by constituent atoms minus the probability that that composed sublattices are not correctly occupied by constituent atoms.
5. A method of judging practical conditions for use of an ordered structure alloy under an irradiation environment, comprising:
preparing an irradiated state diagram that expresses for the ordered structure alloy a relation of a damage rate to a reciprocal of an irradiation temperature on basis of an evaluation formula, related to an effect of irradiation on a degree of long range order S of the ordered structure alloy under irradiation environments, by using as parameters, a first threshold value S th1 at which the degree of long range order begins to decrease, under irradiation, at a rate greater than a rate at which the degree of long range order decreased prior to the first threshold value having been reached, a second threshold value S th2 at which the degree of long range order is nearer to reaching equilibrium than the degree of long range order was prior to the second threshold value having been reached and after decrease of the degree of the long range order which began at the first threshold value S th1 , and the degree of long range order in an equilibrium state S eq ;
for irradiation conditions under which the ordered structure alloy is to be used, calculating a value of the reciprocal of an irradiation temperature of the ordered structure alloy, and corresponding to the value of the reciprocal of the irradiation temperature, finding an S-value, an S th1 -value, an S th2 -value, and an S eq -value; and
comparing the S-value, the S th1 -value, the S th2 -value, and the S eq -value, to thereby predict a damage level and a variation condition of the damage level of the ordered structure alloy under the irradiation environment.
6. The method according to claim 5 , wherein
comparing the S-value, the S th1 -value, the S th2 -value, and the S eq -value, with 0<S eq -value<S th2 -value<S th1 -value<1, and considering a magnitude relation of these values, results in the following judgments being made
(i) when S th1 -value<S-value, the ordered structure alloy is in an ordered state and has a large degree of long range order, corresponding to a low damage level,
(ii) when S th2 -value<S-value<S th1 -value, the ordered structure alloy is in a transition process from an ordered state to a disordered state and the degree of long range order decreases, corresponding to a damage level of the alloy fluctuating greatly and tending to increase rapidly,
(iii) when S eq -value<S-value<S th2 -value, the ordered structure alloy is in a process of reaching a disordered state and an amount of a decrease in the degree of long range order is small while the degree of long range order is small, corresponding to a damage level of the alloy being large but fluctuating little, and
(iv) when S-value<S eq -value, the ordered structure alloy is in a disordered state and the degree of long range order is small, corresponding to a high damage level.
7. The method according to claim 6 , wherein
the degree of long range order S is equal to the probability that composed sublattices are correctly occupied by constituent atoms minus the probability that that composed sublattices are not correctly occupied by constituent atoms.
8. The method according to claim 5 , wherein
the degree of long range order S is equal to the probability that composed sublattices are correctly occupied by constituent atoms minus the probability that that composed sublattices are not correctly occupied by constituent atoms.