2. .'
KB Alloys, Inc. has been a leading
producer of aluminum-based master
alloys since its inception as Kawecki
Chemical Company during 1950.
KB Alloys manufactures a full line of
master alloys, grain refiners, modifiers
and hardeners to meet the metal
treatment and alloying requirements
of the aluminum cast metals industry.
From strategically located manufac-
turing and warehousing facilities in
the USA, Europe and Asia, KB Alloys
delivers consistently dependable prod-
ucts anywhere in the world.
To further serve the aluminum and
non-ferrous foundry industry, KB Alloys'
staff of technical specialists and
experienced field sales engineers
are available for technical assistance.
They are supported by KB Alloys
Metallurgical Services and Technology
Departments.
Aluminum..Base
Master Alloys
Today's foundryman realizes that close
control of the as-cast structure and chemical
composition of the alloy are major require-
ments in the production of quality castings.
Three types of master alloys are essential to
the foundryman: grain refiners, modifiers,
and hardeners.
When grain refiners were first used in
aluminum casting alloys, they were added
as titanium and boron salts to the molten
alloy in the furnace. Alloying elements were
usually added in the form of pure metals.
By present day standards, such practices
are generally inefficient and enVironmentally
unacceptable.
Development of aluminum-base master
alloys in 1955, by Kawecki Chemical
Company, a predecessor of KB Alloys, made
it possible to add the required elements
faster, more economically and above all,
more uniformly than was previously possible.
KB Alloys produces a full line of aluminum-
base master alloys which are convenient
to use and provide the desired elemental
addition. This assures uniformity and pre-
dictability of the required alloy composition.
These I master alloys are available in a
variety of forms: waffle ingot, slab, button,
bar, coiled and cut rod.
A356 alloy as-cast structure. (2X)
TIBOR® Grain Refiners
In aluminum castings, a large dendritic grain
structure is generally undesirable. The most
effective way to provide a fine and uniform
as-cast grain structure is to add nucleating
agents to the melt to enhance crystal
formation during solidification. KB Alloys
TIBORilD family of aluminum master alloys
containing titanium and boron provide
a convenient means of introducing highly
effective nucleating agents.
Grain refinement of aluminum alloys
provides a number of technical and
economic advantages.
Reduced Hot Tearing: Fine equiaxed grains
provide a uniform network of grain bound-
aries, and reduce the tendency for crack
initiation and propagation. In foundry
castings, this structure reduces the tendency
for "hot tearing" and "hot cracking" during
solidification.
Improved Feeding: Fine grains promote
an easier flow of the molten metal that feeds
the shrinkage during the final stages of
solidification, and result in smaller and more
uniformly dispersed shrinkage porosity.
Reduced Porosity: Voids from internal
shrinkage or dissolved gas are intergranular;
with fine grains these voids are smaller
and more uniformly distributed at the grain
boundaries, thus improving the soundness
of the casting.
Better Homogeneity: Secondary phases
and impurities that accumulate along grain
boundaries during solidification are also finer
and more uniformly dispersed.
Improved Mechanical Properties: Grain
boundaries are high energy areas along
which fracture cracks can initiate and
propagate easily. Small closely knit grains
minimize this tendency and provide higher
mechanical properties.
Improved Surface Finish: A fine grain
structure improves the surface finish of a
casting, especially when the piece is bright
dipped or anodized.
Reduced Cost: The improvements which
result from grain refinement of the castings
increase the product yield and reduce
product costs.
A356 alloy grain refined as-cast structure. (2X)
Figure 1

3. - . .
TIBOR@
1
Figure 3. Grain refining response of 5%Ti-1.0%B when added to A356 alloy
containing residual titanium and strontium. Case A ~ 0.005% Ti and no Sr. Case
B =0.005% residual TI and 0.015% Sr. Case C ~ 0.15% residual Ti and no Sr.
Case D ~ 0.15% residual Ti and 0.015% Sr. Grain refiner addition is 2 Ibs per
1,000 ibs A356 alloy in all cases.
0.15
o
o
1.711.4
C
c
Figure 2(a)
Figure 2(b)
B
5.011.0
A
A
In today's practice, Aluminum-Strontium
Master Alloys provide a reliable method
for adding strontium to molten aluminum.
Recovery is high, and loss during hold-
ing is reduced significantly compared to
sodium, even to the extent that aluminum
ingot preViously modified with strontium
can be remelted with good retention of
strontium. This led to the development of
"permanently modified" aluminum silicon
alloys.
Strontium Modification
The search for alternative-elements
for modifying aluminum silicon alloys
revealed that strontium master alloy
could be used in place of sodium.
Fortunately, none of the special precau-
tions required in the use and handling
of sodium apply to the strontium master
alloy, and superior recovery and perfor-
mance are achieved with strontium as a
modifying agent.
4 5 0 . - - - - - - - - - - - - - - - - - - - - .
4 5 0 , - - - - - - - - - - - - - - - - - - - .
4 5 0 . , - - - - - - - - - - - - - - - - - - - .
2001....l...-...J.........-
2OO..J...._....L.._ _
0.005
Residual To (%)
Fogure 1. Grain refining response of 5% Tl-l.0%B and 1.7% Ti-1.4%B When
added 10 A356 alloy having low and high residual To levels. Grain refiner addilion
is 2 100 per 1,000 100 A356 alloy In all cases.
1
Ftgure 2. GraIn refining response of 1.7% TI-1.4%B when added 10 A356 alloy
con1aining residual titanium and strontium. Case A ~ 0.005% Ti and no Sr. Case
B ~ 0.005% residual nand 0.015% Sr. Case C ~ 0.15% residual To and no Sr.
Case 0 = 0.15% residual To and 0.015% Sr. Grain refiner addition is 2 Ibs per
1,000 Ibs A356 alloy in all cases.
.,§ 400
(;
I 350
~
iii 300c;
'E
CJ 250
.,c; 400
~
:[350
~
iii 300c;
'E
CJ250
.,
e400
":[350
..N
;;)300
c;
'E
Cl250
The improvements in properties
that resulted were greatly
responsible for the increase in
use of these alloys. However,
sodium is a very reactive
metal. It can react when ex-
posed to air and can burn
violently during addition to
the molten aluminum silicon
alloy, therefore, close control
and the level of additions
is difficult.
Modification produces a silicon phase that is
fibrous and finely dispersed. Ductility of the
castings markedly improves, and the
tendency for cracking or brittle
fracture is less. For many years,
sodium was the only means
available for the modification of
aluminum silicon alloys.
Modifiers
A major portion of the aluminum alloys used
to produce castings in the foundry industry
contain silicon in the range of 5% to 12%.
When unmodified melts of these alloys
are used, coarse platelet crystals of the
aluminum silicon eutectic phase form in
the casting during solidification. These par-
ticles are brittle and reduce the strength and
ductility of the casting by inhibiting flow of
molten metal ("feeding") into areas of the
casting as it solidifies.
but does contain 0.15% residual Ti. Finally,
Case D which represents the smallest
grain size obtained contained 0.15%
residual Ti and 0.015% Sr. Clearly, when
grain refiner performance is evaluated on a
pound per pound basis, TIBORfI 5%
Ti-1.0%B is the most powerful product for
use with Sr modified alloys such as A356.
After addition to molten
aluminum, sodium tends to
volatilize during holding of
the melt, leading to further
losses. Excessive additions to
compensate for loss can lead
to "over modification" with the
formation of coarse AI-Si-Na
compounds and SUbsequent
deterioration in structure
and mechanical properties.
The need for a non-sodium
modifier was clear.
2001....l..._...J..._ _
Grain Refiner Interactions
In the production of foundry alloy ingot, it
is common practice for the ingot producer
to add titanium to his alloy to enhance the
alloy's response to later additions of TIBOR(!l
grain refiners. We commonly refer to this
as "residual titanium" and it is typically
present at levels ranging from -0.15 - 0:30%.
In addition, aluminum-silicon foundry alloys
are typically modified via additions of
strontium, either by the ingot producer or by
the foundryman.
KB Alloys Technology Group has studied
these factors and interactions relative·to the
performance of 5% Ti-1.0%B and 1.7%
T-1.4%B TIBORfI. It was confirmed that both
products producer a smalle grain size
when added to an alloy containing residual
titanium as illustrated in Figure 2(a). In both
cases, the grain size was reduced from -415
microns to -355 microns.
This work also investigated possible
interactions between strontium and grain
refiners. In the presence of strontium,
TIBOR® 5% Ti-1.0%B produces a smaller
grain size than does TIBORfi 1.7%T-1.4%B.
In fact, no interaction was observed between
strontium and TIBOR@ 1.7% Ti-1.4%B as
demonstrated in Figure 2(b). The results
however are different with 5%Ti-1 %B as
illustrated in Figure 2(c). The largest grain
size is represented by Case A where
there was no Sr addition and residual Ti
was at the low level of 0.005%. Case B is
the same as A, but includes a Sr addition
of 0.015%. Case C received no Sr addition,
KB Alloys TIBOR(!l family of master alloy
grain refiners are available in a range of
chemical compositions and titanium to
boron ratios. Howeverthe most effective and
most commonly used grain refiners for
aluminum casting alloys contain either
5% Ti-1.0% B or 1.7% Ti-1.4%B. Both
products are available in button, waffle
ingot, bar, coiled and cut rod form.
Choice of TIBOR® Alloy for
Grain Refinement
KB Alloys produces TIBORfi in button,
waffle ingot, bar, coiled and cut rod form.
Product form and performance attributes
can be tailored to fit customers production
practices.
Beyond the differences in chemical com-
position, the intermetallic boron phases
differ significantly between the two products.
In the 5%Ti-1%B composition, the boron
intermetallic phase is present as TiB2
particles. The 1.7%Ti-1.4%B composition
has a "mixed boride" intermetallic phase.
Figure 2(c)

4. 0 ••1 I~.l
Aluminum-Strontium
Master Alloys
KB Alloys produces and markets a variety
of aluminum master alloys containing
strontium.
A residual concentration of 0.01 % to
0.02% strontium is usually adequate for
full modification of hypo-eutectic and
eutectic alloys. However, excess additions
do not cause over modification, although
concentrations greater than about 0.1 %
should be avoided because detrimental
AISrSi intermetallics may start to form.
Furnace practice, alloy composition, and
solidification rate of the casting will influence
optimum level to be used in production.
Proper strontium additions to aluminum
silicon alloys improves as-cast mechanical
properties. Improvements in elongation
from 50% up to 200% can be achieved.
Increases in ultimate tensile strength of 20%,
have been reported as well as improved
surface texture and machinability perfor-
mance of the castings.
There is evidence that strontium promotes
the formation of finer particles of iron-rich
intermetallic compounds instead of the
relatively large particles of more brittle iron-
aluminum-silicon phase. These fine particles
increase the ductility of aluminum silicon
casting alloys with high iron content.
As shown in Figure 2(c) strontium additions
promote a positive interaction with titanium
and boron. Together strontium and TIBOR~
interact to further refine grain structure
than TIBO alone. KB Alloys TIBOR-
products are an ideal family of grain
refiners for use in both modified and
unmodified alloys.
Summary
1. KB Alloys strontium aluminum master
alloys provide reliable, effective means
of adding strontium to modify
aluminum alloys.
. 2. Castings made from melts properly
modified with strontium are more sound
and have significantly improved
mechanical properties, particularly
ductility, than castings made with
unmodified melts.
3. Strontium is a more cost effective
modifier than sodium for aluminum
silicon hypoeutectic casting alloys.
Under controlled conditions, strontium
modified ingots can be remelted and
retain the modified structure.
4. The use of aluminum strontium
master alloys avoids the need for the
special precautions associated with
use of metallic sodium.
5. Strontium tends to reduce the size of
the iron-rich compounds, if present,
resulting in improved ductility of
iron-containing aluminum silicon
casting alloys.
6. Strontium modified ingot and sodium
modified ingot may be melted and mixed
together without loss of modification. If
the modification melt mixture requires
al;lditional modification, more strontium
may be added to obtain the desired
structure.
7. Additions of sodium as a metal to a
melt of strontium modified ingot are
not recommended because of the
Strontium modified, as-cast
structure of A356 alloy.
Note finely dispersed fibrous
structure of silicon phase. (400X)
possibility of "over modification", i.e.,
formation of undesirable AL-Si-Na
compounds.
8. Degassing of a strontium modified
melt should be performed_ with dry
nitrogen or argon gas.
9. The use of salts for grain refining or
fluxing should be avoided because
chlorine and flourine will remove
strontium from the melt.
10. Phosphorous, even in small amounts
should be avoided because it will '
poison the ability of strontium to
modify the silicon phase.
11. When grain refiner performance is
evaluated on a pound for pound basis,
TIBOR- 5%Ti-1 %B is the most powerful
and effective grain refining product for
use with strontium modified alloys such
as A356.
Unmodified, as-cast structure of
A356 alloy. Note the coarse
platelet crystals of silicon
eutectic phase. (400X)
Figure 3

5. AluQ'linum Hardener Alloys
Alloying elements are added to aluminum
to improve the mechanical and physical
properties of the final product. In order
to overcome the disadvantages of add-
ing pure elemental metals to the melting
furnace, aluminum-base master alloys were
developed that are rich in one or more of the
desired addition elements. This family of
master alloys, frequently referred to as
hardeners, is used to add alloying elements
to aluminum to produce alloys with improved
strength, hardness, fracture toughness
and corrosion resistance. Master alloys of
copper, magnesium, manganese, bismuth
and chrome are examples.
68% Mg
KB Alloys introduced a new formulation to
its magnesium aluminum hardeners line of
alloys. By raising the concentration of
magnesium from the traditional 25% and 50%
levels to that of 68%, the new formulation
takes advantage of the traditional benefits
associated with the use of a master alloy,
while the higher composition rivals the
economics of alloying with pure magnesium
through the benefits of better recoveries,
improved through-put with lower melting
points and cleaner melts.
The new product is exclusiv~ to KB Alloys
and comes in a variety of sizes and forms to
suit the needs of a wide range of customer
applications. The 3.5 ounce button is
designed for small furnace alloying or
"touch-up" for larger additions. The waffle
and slab ingots provide a convenie'nt alloying
method for medium to large furnace
additions. All shapes are produced
under an ISO registered process to insure
consistent chemical composition, ingot
weight control and metallurgical cleanliness.
The 68% Mg product is design~d to benefit
the experienced alloyer. Because the density
is greater than that of pure magnesium
(2.0g/cc vs. 1.7g/cc) the 68% Mg-AI
alloy has less tendency to float and burn-off.
Less burn-off means fewer oxides, better
recoveries and cleaner melts. With its low
melting temperature (43rC vs 650°C) the
68% Mg alloy melts ultra-fast to keep
production lines moving.
Modification Rating System for
Hypoeutectic Aluminum Silicon
Alloys
The structure of an aluminum casting varies
with different casting parameters and must
be controlled in order to provide consistent
castings. To achieve optimum properties, it
is necessary to modify the morphology of
the eutectic phase in hypoeutectic aluminum
silicon casting alloys. The cast structure of
hundreds of aluminum silicon alloy samples
have been examined to establish the degree of
modification. (1) Extensive experience with
Aluminum Association Alloy A356, which
contains 6.5-7.5% silicon and 0.20-0.45%
magnesium, has led to the formulation of
the silicon phase modification rating system
shown in Figure 4.
1. D. Apefian. G. K. Sigworth and K. R. Whaler: "Assessment of
Grain Refining and Modification of AISi Foundry Alloys by Thermal
Analysis", AFS 7{ansactions. pp. 297-307 (1984).
Sample Preparation
A small section is cut from the casting to be
examined, then polished on successively
finer grits of SiC sandpaper until a smooth
and flat surface is obtained. The sample can
then be polished on cloth wheels
using "A" and "B" grade aluminum oxide
powders until a mirror-like shine is
observed. The silicon phase can clearly be
seen at 200x on the as-polished surface; a
brief etch in a 5-10% HF solution will darken
the silicon phase to make viewing easier.
Master Alloys
Sample Evaluation
The polished sample is examined at
(200X) magnification.
The microstructures observed can be
placed in one of six overall classes.
These are listed on Figure 4 with a
numerical scale of Type 1 through
Type 6 along with a description
of the structure. Photomicrographs
of each type of structure at 200X are
presented for use as standards
representative of each class.
It is now possible to assign any casting
of hypoeutectic AI-Si alloy, a numerical
value, which reflects its internal
structure to that of the rating system
shown in figure 4.

6. Modification Rating System (200x)
Type 1. Fully Unmodified Structure
Type 2. Lamellar Structure
Type 3. Partial Modification Structure
Figure 4
. ~~'-..,c ...... _
",.' -~ .
Type 4. Non-Lamellar Structure
Type 5. Modified Structure
Type 6. Super Modified Structure

7. ~~~~~===================================~~---------
FOUNDRYMEN'S GUIDE TO GRAIN REFINER ADDITIONS*
SELECT CHARGE SIZE, CHOICE OF TIBOR·, PRODUCT FORM. READ QUANTITY REQUIRED.
TIBOR· 5%Ti /1 %B TIBOR·l.7%Ti /l.4%B
Nominal addition level: Nominal adClition level:
2 Ibstl,OOO Ibs (0.01 %Ti) 2 Ibst1 ,000 Ibs (0.01 %TO
.907 kg/454 kg (0.01 %Ti) .907 kg/454 kg (0.01 %Ti)
5%TI/1%8 'CUT 'WAFFLE Kg WAFFLE 1.7%Ti/1.4%B 'CUT 'WAFFLE
CHARGE TIBO~
ROD "BUDON SECTION INGOT INGOT TIBO~
ROD "SUDON SECTIONGRAIN GRAINSIZE REFINER (1 oz) (50z) (1 Ib) (2.2Ibs) (16Ibs) REFINER (1 oz) (50z) (1 Ib)
(Ibs or kg) REQUIRED (.03 kg) (.14 kg) (.454 kg) (1 kg) (7.25 kg) REQUIRED (.03 kg) (.14 kg) (.454 kg)
100lbs 0.21b 3 1 0.21b 3 1
45 kg .1 kg Rods Button .1 kg Rods Button
250lbs 0.51b 8 2 0.51b 8 2
113 kg .23 kg Rods Buttons .23 kg Rods Buttons
500lbs 1 Ib 16 3 1 1 Ib 16 3 1
26 kg .454 kg Rods Buttons Section .454 kg Rods Buttons Section
1,0001bs 2 Ibs 7 2 1 21bs 7 2
454 kg .907 kg Buttons Sections Ingol .907 kg Buttons Sections
1,5001bs 31bs 10 3 1 31bs 10 3
680 kg 1.36 kg Buttons Sections Ingol+ 1.36 kg Buttons Sections
2,0001bs 4 Ibs 13 4 2 41bs 13 4
908 k9 1.81 kg Buttons Sections Ingots 1.81 kg Buttons Sections
5,0001bs 10lbs 10 5 10lbs 10
2268 kg 4.54 kg Sections Ingots 4.54 kg Sections
10,0001bs 20lbs 20 9 1 20lbs 20
4540 kg 9.07 kg Sections Ingots Waffle+ 9.07 kg Sections
4
Sections
,
*Note: The addition levels shown are typical. Depending upon the casting method employed and the difficulty of the alloy, it may be necessary to
increase the addition level by a factor of 2 to 3x.
FOUNDRYMEN'S GUIDE TO STRONTIUM ADDITIONS*
SELECT CHARGE SIZE& CHOICE OF STRONTIUM MASTER ALLOY. READ QUANTITY REQUIRED.
r
I
STRONTIUM MASTER ALLOY 1O%Sr / AI
Nominal addition level:
,
1.5 Ibst1 ,000 Ibs (0.15% Sr) .68 kg/454 kg (0.15%Sr)
CHARGE
STRONTIUM CUT WAFFLE WAFFLE
MASTER ROD SUDON SECTION SECTION
SIZE ALLO~ (1 oz) (80z) (1 Ib) (16Ibs)
'(Ibs or kg) REOUIR (.03 kg) (.23 kg) (.454 kg) (7.25 kg)
100lbs 0.151b 3
45 kg .07 kg Rods
250lbs 0.381b 6 1
113 kg .17 kg Rods Button
500lbs 0.751b 12 2 1
26 kg .34 kg Rods Buttons Section
1,0001bs 1.51b 24 3 2
454 kg .68 kg Rods Buttons Sections
1,5001bs 2.251bs 5
680 kg 1.02 kg Buttons
2,0001bs 3 Ibs 6 3
908 kg 1.36 kg Buttons Sections
5,0001bs 7.51bs 15 8
2268 kg 3.4 kg Suttons Sections
10,0001bs 151bs 15 1
4540 kg 6.8 kg Sections Waffle
*Note: The addition levels shown are typical. Depending upon the casting method employed and the difficulty of the alloy, it may be necessary to
increase the addition level by a factor of 2 to 3x.