PtdDWX

Metglas ®
Amorphous
Brazing Foil Overview
Page 1
Privileged and Confidential

Metglas ® Brazing Foil – Essence of Brazing
In brazing/soldering we deal with and
successfully manipulate matter and its structure,
space (dimensions), energy (temperature) and
time.
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How is Amorphous Brazing Foil (MBF) Made?
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What Makes Metglas ® Amorphous Brazing Foil (MBF) Unique?
Our manufacturing process gives
Metglas ® filler metals the ultimately
uniform atomic structure
Conventional brazing filler metals of the
same composition have a crystalline
structure with different segregated phases
Metglas ® Brazing Foil
• Ductile, Flexible, 100% Metallic Foil
• Melts Quickly within a Narrow Temperature
Range
• Creates Strong and Non-porous Joints
• Can Be Placed with Precision i Between Parts
• Very Economical and Effective Vs. Powder
Metal Fillers, Low Erosiveness
• Reduces Set Up & Assembly Process Time
• Does not Harm the Environment and Vacuum
Brazing Furnaces
Conventional Brazing Filler Metals
• Generally Brittle Powders
• Melts Slower than MBF within a Wider
Temperature Range
• Excessive Amount of Detrimental Oxides
• Larger Quantities Required per Joint than MBF
• Prone to Form Porous Joints with Large
Crystal Grains
• Messy and Difficult Assembly Processing
• Contaminates the Environment and Degrades
Vacuum Brazing Furnaces
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Metglas ® Brazing Foil
Advantages of Amorphous Brazing Foil
METALLURGICAL TECHNOLOGICAL MANUFACTURING
• 100% dense and ductile
metallic foil
• Fine and uniform
microcrystalline structure
before melting
• Predictable, uniform joint
• No need for strong
capillary action to carry filler
to the joint
• No problems such as loss
of fbi binder during heating
• Stop waste-precise
metering vs. past and
powder
• Fast melting in a narrow
• High purity from oxides
• Infinite shelf life
temperature range
• Instant formation of the • Reduces erosion thin • Reduced set up &
liquid front at the joint
interface.
gauge parts
assembly process time
• Avoids clogging of
channels and dh holes.
• Self fluxing in Cu-toCu
applications
• Reduces rejects and
reworks
• Controls brazing filler cost
• Precise placement of foil
within a joint
Page 5
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Three Types of Stainless Steel Joints Using Amorphous Foil
50 um
FeCr /
MBF50
120 um 50 um
50 um
135 um
304L /
MBF51
50 um
316L / MBF51,
Annealed
after Brazing
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Effect of the Filler Metal Thickness and Brazing Time On Joint Structure
50 um
50 um
50 um
Always consider the importance of mechanical properties and morphology of
segregated phases, particularly hard and brittle intermetallics such as (Cr/W/Ti)
borides, nickel silicides, Cu phosphides and silicides, etc.
They are frequently the sources of cracks appearing when stressed and their
presence leads to brittle joint failure (see following slide).
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Effect of the Filler Metal Thickness and Brazing Time On Joint Structure
50 um
120 um 50 um
50 um
135 um
Microstructure of two 436 stainless steel plate/fin samples brazed using 25 μm thick (a) and
50-μm thick (b) MBF20 foil. Note that while inside of the brazes the joint thickness is the
same, the cross-section of the 50-μm joint 50 is um larger than that of the 25-μm joint. The former
is wider and the fillet height is higher. Therefore, the 50-μm joint is substantially stronger. 13
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Effect of the Filler Metal Thickness and Brazing Time On Joint Structure
a
50 um
120 um 50 um
b
50 um
Samples of brazed plate/fin 436
stainless steel structures: (a) In
the as-brazed state after electro
erosion 135 um cutting; (b) After failure
under mechanical testing in the
tensile mode at 650°C.
50 um
Page 9
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Effect of the Filler Metal Thickness and Brazing Time On Joint Structure
50 um
Joint Mechanical Properties - Lap Joint 1:1 Overlap
120 um 50 um
50 um
135 um
50 um
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Metglas ® Brazing Foil -- Available Chemistries
Metglas ® Brazing Foil
MBF
Alloy
AWS & ASM
Classifications
Melting Temp. C° Braze
Nominal Composition, wt %
Temp.
(F°)
(Approx.)
Cr Fe Si C* B P Mo Ni Solidus Liquidus C° (F°)
Density
g/cm 3
(lbm/in 3 )
15 13.0 4.2 4.5 0.03 2.8 - - Bal 965 (1769) 1103 (2017) 1135 (2075) 7.82 (0.283)
20 AWS BNi2 /AMS 4777 7.0 3.0 4.5 0.06 3.2 - - Bal 969 (1776) 1024 (1875) 1055 (1931) 7.88 (0.285)
30 AWS BNi3/AMS 4778 - - 4.5 0.06 3.2 - - Bal 984 (1803) 1054 (1929) 1085 (1985) 8.07 (0.291)
50 AWS BNi-5a 19.0 - 7.3 0.08 1.5 - - Bal 1052 (1924) 1144 (2091) 1170 (2138) 7.70 (0.278)
51 AWS BNi-5b 15.0 - 725 7.25 006 0.06 14 1.4 - - Bal 1030 (1886) 1126 (2058) 1195 (2183) 773(0278)
7.73 (0.278)
53 15.0 - 7.25 0.06 1.4 - 5.0 Bal 1045 (1900) 1127 (2060) 1195 (2183) 7.75 (0.280)
60 AWS BNi-6 - - - 0.10 - 11.0 - Bal 883 (1621) 921 (1688) 950 (1742) 8.14 (0.294)
62 21.0

Metglas ® Brazing Foil – Maximum Width by Thickness
Metglas ® Brazing Foil
Maximum Foil Width by Thickness
ALLOY
.0010" .0015" .0020" .0025" .0030"
(25.4 µm) (38.1 µm) (50.8 µm) (63.5 µm) (76.2 µm)
MBF15
85" 8.5" 85"
8.5"
(215.6 mm) (215.6 mm)
MBF20
MBF30
MBF50
MBF51
MBF53
MBF60
MBF62
MBF64
MBF80
8.5" 8.5" 8.5" 8.5" 8.5"
(215.6 mm) (215.6 mm) (215.6 mm) (215.6 mm) (215.6 mm)
8.5" 8.5" 8.5" 8.5" 8.5"
(215.6 mm) (215.6 mm) (215.6 mm) (215.6 mm) (215.6 mm)
6.5" 6.5"
(165.1 mm) (165.1 mm)
8.5" 8.5" 8.5" 8.5" 8.5"
(215.6 mm) (2156mm) (215.6 (2156mm) (215.6 (215.6 mm) (215.6 mm)
4.0" 4.0"
(101.6 mm) (101.6 mm)
3.0" 2.0"
(76.2 mm) (50.8 mm)
6.7" 8.5" 4.0"
(170.18 mm) (215.6 mm) (101.6 mm)
6.7" 8.5"
(170.18 mm) (215.9 mm)
20"
2.0
(50.8 mm)
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Privileged and Confidential

Principles To Follow When Choosing Filler Metal Composition
Principles To Follow When Choosing
Filler Metal Composition:
• T melt (FM) < T melt (BM)
• γ L (FM) < γ S (BM)
• Compatibility and affinity of FM and BM
o Relevance of compositions and joint
service requirements
o Similarity in crystal structure
o Strong bonding at FM/BM interface
(importance of γ FM/BM , epitaxy at the ceramic/metal interface)
• Presence of chemically, physically active elements: self-fluxing
• Optimal joint microstructure upon crystallization/post-brazing annealing
• Complacency of brazing operations with BM properties, existing equipment, and
economics
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Privileged and Confidential

Major AWS Classes of Brazing Filler Metals
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Privileged and Confidential

Preform Vs. Powder
Preforms
Which to Use?
Powder
• Vertical Joint
Orientation
• Accurate Amount of
Filler Metal Applied is
Critical
• No Sooting is Acceptable
• Extended Time Between
Application and Brazing
• Broad Temperature
Window for Brazing
• Horizontal Joint
Orientation
• Consistent Application
Technique
• Minor Sooting on the
Part is Not Critical
• Brazing Shortly After
Application of Filler Metal
• Application Requires
Good Filler Metal Flow
at Lower Temperatures
or Shorter Time at
Temperature
CHARACTERISTICS OF THE APPLICATION
Figure 3: This schematic shows the
characteristics of each filler method.
From Allen, K., Feldbauer, S., “The Brazer’s Question: Paste or Preforms?”, Weld. J., 2007, 86, N3, pp.
55-57
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Metglas ® Foil Vs. Powder/Paste
Cost Savings & Performance Advantages
Metglas ®
Cost Savings
Foil Vs. Powder/Paste
Performance Advantages
* Reduced Set Up and Manufacturing
Process Time
* Eliminates Error and Waste Through
Precise Metering
* Eliminates Rejects and Rework Time
with Uniform and Consistent Braze Joints
* Eliminates Harmful Organic Binders
* Eliminates Joint Porosity (No Filler Metal
Shrinkage)
* Cleaner Furnace
* Controls Brazing Costs * Reduced Dependence on Capillary Action
to Distribute Filler Metal
* Improves Overall Efficiency of the
Manufacturing Process
* Reduced Oxide Content in Joint
* High Purity and High Strength Joints
* Infinite Shelf Life
Fillets formed by MBF-20
foil and BNi-2 paste on 409 stainless steel joints brazed under -40°C FP
50:50
N 2
:H 2
atmosphere at 1115°C for 10 min.
Note incomplete flow and crevices formed on a
sample brazed with the paste.
Page 16
Privileged and Confidential

Metglas ® Brazing Foil – Ideal Applications
IDEAL APPLICATIONS INCLUDE:
• Oil Coolers
• EGR Coolers
• Fuel Coolers
• Heat Exchangers
• Metallic Catalyst Substrates
• Diesel Exhaust Components
Page 17
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Stainless Steel Tube/Fin Steam Generators
Stainless Steel Tube/Fin Steam Generators with Enhanced
Oxidation/Corrosion Resistance (courtesy of IST, Canada)
General view of a power station fitted
with IST steam generators.
IST fin/tube steam generators
manufactured using a few miles of
tubes to which fins are brazed using
MBF-foil. These finned tubes are
welded together after brazing
operation.
Sample of SB423 pipe on
which 409 fin and MBF51 foil
are wound around pipes in a
semi continuous assembly
line before brazing.
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Heat Exchanger Applications – Heat Recycler
HEAT RECYCLER
Waste heat recovery systems are gaining popularity because of rising energy costs. This
finned tube heat exchanger recovers waste heat as steam for a Rankine cycle turbine.
Brazing Application
Fins must be brazed up to 30m of indivisible lengths to the tube. Approximately 22 km
of tubing may be used in a single exchanger.
High flexibility and the ability to resist
tension and crushing during assembly are crucial. High strength, corrosion resistant
joints with a uniform thickness are essential. Brazing filler metals in powder and
powder-binder composites are poor candidates because of contaminating residues and
possible joint shrinkage.
Solution
MBF offers the advantage of a completely automated process, purity and consistent
thickness. Each tube is rotated to wrap it with foil and fin. The machine tensions
brazing foil and fin stock as it turns the tube. The fins are crimped at one edge which is
pressed tightly against the brazing foil. The assembly is moving continuously through
an induction heating station under the cover of pure Nitrogen. Brazing occurs when the
assembly passes through the high powered heating zone at 1065°C for 1–2 minutes.
Easy automation and low manufacturing costs are provided.
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Heat Exchanger Applications –
Plate-Fin Heat Exchanger and Plate-Plate Heat Exchanger
PLATE-FIN
HEAT EXCHANGERS
Brazing Application
High efficiency use in demanding installations where light weight, corrosion resistant and high
performance are necessary, such as aerospace and automotive exhaust applications.
Solution
MBF foil thickness can be controlled to provide at least 15% weight savings over similar powder
alloys. Without binders or adhesives, the MBF joint is typically stronger than comparable
powder, paste or tape joints by insuring clean, consistent, non-porous and complete joint
coverage.
PLATE-PLATE HEAT EXCHANGERS
Brazing Application
The ability to resist corrosion in deionized water, ammonia, and other harsh chemical systems
while sustaining design pressures up to 1760 psi (120 bar).
Solution
MBF series alloys are corrosion resistant to ammonia and other corrosive environments. High
resistance to sulfuric, phosphoric, and nitric acids make MBF foil an ideal brazing filler metal for
austenitic stainless steels.
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Heat Exchanger Corrosion Results
Corrosion results of 316L Heat Exchangers Brazed with Cu or
MBF51 After Exposing to Various Solutions for >300 h
Solution
240 mg/L sulfate as sodium
sulfate
Heat Exchanger Brazement Materials
316L/Cu 316L/MBF51
Cu removed from the
samples, heavy black No traces of corrosion
corrosion products.
100 mg/L chloride and 80
mg/L sulfate as sodium salts
500 mg/L sulfate as sodium
sulfate
500 mg/L chloride as sodium
chloride
Thin layer of Cu 2 O is
formed
Joints show uniform
corrosion. Uniform layer
is formed.
Joints are covered by
thick crystallized Cu 2 O
layer; strong uniform
joint corrosion.
No traces of corrosion
No traces of corrosion
No traces of corrosion
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Metallic Catalytic Substrate
METALLIC CATALYTIC SUBSTRATE
In recent years, metallic catalyst substrates have begun to replace the
ceramic substrates used to filter emission particulates. In
addition to being sturdier and resilient to vibration and enabling
the unit to be mounted closer to the engine, the metallic substrates
heat up faster to reduce harmful emissions.
Brazing Application
The cells of these units are formed by utilizing i approximately 50–100µm(2.0–4.0mil) thick
corrugated and flat sheet stock. The concentrically wrapped metal sheet must be securely
fastened to itself to prevent vibration and potential release of catalyst during engine operation
(which would result in unit failure). Brazing is an important technique for manufacturing the
advanced metallic catalytic converters.
Solution
When using MBF instead of powder or pastes,
smaller, high-quality fillets are formed.
As a result, cells become more open, thereby
reducing exhaust backpressure. MBF foils
leave more effective surface area for the
catalyst. Finally, process automation is easily
achieved with ductile MBF foil.
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Aerospace – Compressor Vane & Shroud Assemblies (Stators)
Compressor Vane and Shroud Assemblies (Stators)
These stationary components are set between rotating blade assemblies in the compressor
section of jet turbine engines. They guide airflow between blade stages, critical to increased
engine efficiency.
Brazing Application
12 to 15 stators may be used in an engine, with each stator requiring attachment of 100+ airfoil
vanes to a shroud ring. High strength, corrosion resistant, economical joints with uniform gap
are required.
Solution
Brazing powder and powder-binder composites may be used, but these leave contaminating
residues and promote joint shrinkage and brazing rejects. MBF is simply tack welded into place
on the shroud ring and the vanes are assembled and fixtured with an expansion ring for
brazing. Clean, nonporous joints are formed upon brazing.
Note Metglas ® , Inc./Hitachi Metals America policy prohibits the
utilization of our products in weapons of mass destruction and missiles.
The resulting stator exhibits precise,
uniform joints on each vane.
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Privileged and Confidential

Aerospace – Rotating Blade Porous Metal (Feltmetal) Seals
Rotating ti Blade Porous Metal (Feltmetal
Feltmetal) t l) Seals
These seals are used in the rotating blade assemblies of jet turbine engines. They are designed
to wear down from the blade rotation and then be periodically replaced.
Brazing Application
20 or more of these seals may be used in an engine. Each seal is brazed to a backing ring and
requires uniform joint gap and minimal wicking. If excessive wicking occurs, the feltmetal will
damage the more complex and costly blade assembly.
Solution
MBF is sandwiched between the backing ring and feltmetal, fixtured with an expansion ring, and
brazed. Ultra-thin custom-designed MBF meets the specified dimensional tolerance to avoid
excessive wicking, simplifies the process, and eliminates rejects.
Note Metglas ® , Inc./Hitachi Metals America policy prohibits the
utilization of our products in weapons of mass destruction and missiles.
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Privileged and Confidential

Aerospace – Rotating Blade Porous Metal (Feltmetal) Seals
Brazing Honeycomb To Perforated Face Sheets (Sandwich)
Honeycomb structural panels are widely used in aerospace applications since they offer
exceptional strength/stiffness-to-weight ratio. Acoustic turbine tailpipes, exhaust plugs, cones,
nozzles and fan ducts are often brazed as honeycombs.
Brazing Application
For acoustic or sound attenuation structures, the brazing filler
alloy must flow off the honeycomb surfaces to form fillets at
all the junctions without clogging the perforations, which are
needed for sound absorption. Residues left by other brazing
fillers clog the perforations, leading to joint rejects.
Solution
By tack welding the MBF to the face sheets, capillary action
draws the melted brazing foil to the thin edges of the honeycomb
structure, while keeping it out of the perforations. Joint
strength is improved because the foil acts as a spacer to
maintain an optimum joint gap. Filler metal flows only in
necessary contact area.
Note Metglas ® , Inc./Hitachi Metals America policy prohibits the
utilization of our products in weapons of mass destruction and missiles.
Page 25
Privileged and Confidential

For additional information on Metglas and
Metglas ® Brazing Foil, please visit our website at:
www.metglas.com
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