Page 417 - Fundamentals of Magnetic Thermonuclear Reactor Design

Structural and Functional Materials Chapter | 13 395

TABLE 13.2 Chemical Composition of High-Strength Copper Alloys
Alloy (trademark, manufacturer) Composition (wt%)
Precipitation-hardened alloys
BRKhTsR (Giprotsmo) Cu–Cr (0.60)–Zr (0.05)
MZC (Amax Copper, Inc) Cu–Cr (0.80)–Zr (0.15)–Mg (0.04)
ELBRODUR G (Kabelmetall) Cu–Cr (0.65)–Zr (0.10)
C17510 (Brush Wellman, Inc) Cu–Ni (1.4–2.2)–Be (0.2–0.6)
Al 2 O 3 dispersion-strengthened alloys
MAGT 0.05 (Special alloy) Cu–Al (0.1)–Hf (0.01)–Ti (0.03)–Al 2 O 3 (0.20)
MAGT 0.2 (Special alloy) Cu–Al (0.25)–Hf (0.01 ÷ 0.10)–Ti (0.03–
0.14)–Al 2 O 3 (0.5)
GlidCopAl 15 (SCM Metals) Cu–Al (0.15)–Al 2 O 3 (0.28)
GlidCopAl 25 (SCM Metals) Cu–Al (0.25)–Al 2 O 3 (0.46)
GlidCopAl 60 (SCM Metals) Cu–Al (0.60)–Al 2 O 3 (1.12)

Investigations carried out in the mid-1980s showed that these alloys can be
regarded as candidate materials for high power loaded MFR components [10].
They are not prone to swelling and embrittlement. Experimental data gathered
over the past two decades cover the behaviour of copper alloys at temperatures
between 50 to 350°C and radiation loads of up to 2 dpa [11]. Generally, they
are consistent with the operational scenario envisioned for the ITER reactor.
The most valuable practical result of those investigations is representative
information regarding the radiation resistance of copper alloys and bimetallic com-
pounds (Cu//SS) type manufactured using the hot isostatic pressing (HIP) process.
Three radiation-induced processes have a critical effect on the service life
of a copper alloy used in the MFR. They are the low-temperature radiation
embrittlement (at irradiation temperatures of 150–200°C), vacancy swelling (at
≥300°C) and transmutants accumulation resulting from thermal conductivity
degradation due to neuron irradiation. Cu–Cr–Zr alloys are highly resistive to
radiation embrittlement and swelling before and after the HIP treatment.
In a dose–temperature range expected in ITER, the Cu–Cr–Zr IG//316L(N)
HIP-compound maintains adequate plasticity and resistivity to cyclic thermal
fatigue. The mechanical properties of bimetallic compounds before and after
irradiation are close to those of original copper alloy. We emphasise again that
the adequacy of existing experimental data remains a grey area because of the
considerable difference between the neutron flux energy spectra in the fission
and the fusion reactors. At the same time, the harder fusion spectrum may give
rise to a number of adverse effects, such as the following:
−3
l faster (up to 2 × 10 at.% per 1 dpa) helium accumulation, leading to a
more intense HTRE and swelling,