Erratum to: Advanced lightweight alloys for aerospace applications
Figure 6. Microstructural development of the unidirectionally solidified casting. (a) As cast. (b) Solutionized at 1,093°C for 9 hr. (c) Solutionized, and then aged at 510°C for 3 hr. Table II. Hardness Improvement Through Double Heat Treatment Solutionized at As-Cast 1,093°C for 10 hr.
-'-Room Temp. 343'C 1,038'C
Investment Mold Temperature
Property or Characteristic
Casting Range (OC)
Tensile Modulus (GPa)
Thermal Conductivity at 100°C (W/m'K)
within the primary nickel matrix. It is this
matrix phase which provides hardening
through precipitation after the aging treat
The Vickers microhardness and Rock
well hardness in the as-cast, solutionized,
and aged conditions are compared in
Table II. The Vickers hardness in the as
cast condition is 358, which decreases
significantly upon solutionizing through
the eliminationof microsegregation. Then
the hardness of the material increases to
474 after the aging treatment. The Rock
well hardness (Rc) follows a similar trend.
The alloy also offers good strength in the
as-cast condition, which is further im
proved by the two-step heat treatment
(i.e., solutionizing and aging).
Table III compares the properties of
8erylco 42C with AISI304 stainless steel.
The casting temperatures for the 42C al
loy are 1,230-1 ,343°C, and, for stain
less steel, the corresponding range is
1,482-1 ,593°C. The lower casting tem
peratures give manufacturing flexibility
during processing by using lower cost
nonferrous materials and processes. The
modulus values are comparable. The
Solutionized + Aged
at 510°C for 3 hr.
Rs = 84
Rc = 38
tensile strength is almost double that of
stainless steel, and the 6% elongation in
castings is considered adequate in many
applications. The important aspect to
note is thatthe thermal conductivity ofthe
material is nearly twice that of stainless
steel, enabling rotating applications where
heat dissipation is a critical attribute.
The authors thank NGK Metals Cor
poration andArwood Corporation, where
this work was conducted, for permission
to publish this paper.
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tAZ91 C is a currently used alloy shown lor comparison.
1. "Berylco Beryllium Nickel Alloys," Product Application Review , NGK Metals Corporation , Reading, PA.
2. E. W. Filer , "Nickel-Beryllium Alloys Resistance to Sullide Stress Cracking," Corrosion Microstructure and Metallogra· phy, 12 ( 1985 ), pp. 89 - 101 .
3. Y.V. Murty , T.Z. Kattamis , R. Mehrabian and M.C. Flemings , " Behavioral Sullide Inclusions During Thermomechanical Processing 01 AISI 4340 Steel," Metallurgical Transac· tions A , 8A ( 1977 ), pp. 1275 - 1281 .
4. Metals Handbook , Desk Edition (Metals Park, Ohio: ASM, 1985 ), pp. 23 . 21 - 23 . 26 .