Aluminum Boron Alloy

Alloy Description:

No ImageAluminum Boron master alloy is the alloy of Aluminium and Boron which is used as additive for Boron in aluminum alloys as a hardener and grain refiner. This alloy is dissolved fast in aluminum melt and gives maximum recovery of Boron than the Boron added individually. AlB is an exceptional alloy choice for making aluminum for electrical conductors. The chemical composition and physical properties of the Aluminium Boron master alloy is given below:

Chemical composition:

Alloy Grade Chemical composition (%)
B Fe(max) Others (max) AI
AlB 3 2.5-3.5 0.25 0.5 Balance
AlB 4 3.5-4.5 0.25 0.5 Balance
AlB 5 4.5-5.5 0.25 0.5 Balance

Other impurities- Mn, Ca, Zn, Na, Si, Pb **above hardeners are produced from 99.7% (Min.) purity of Al.

Physical properties:

Alloy Grade Density (gm/cc) Melting point (°C)
AlB 3 2.5 – 2.6 690 – 700*
AlB 4 2.5 – 2.55 710 – 720*
AlB 5 2.45 – 2.5 725 – 730*
* melting point is not a relevant in normal use, the majority of
master alloy and tablets produced by Minex Metallurgical Co.
Ltd., dissolve in Aluminium rather than melt.

Addition technique:

Remove heavy dross from melt surface and add appropriate amount of AlB master alloy (At T 720 - 760°C). After the dissolution of alloy, stir the melt gently for 30sec.

No ImageAluminium Boron master alloy has been added in experimentally in aluminum alloys as a Boron additive. As aluminum is most widely used material for electrical conductors, due to its excellent electrical conductivity, good mechanical properties and favorable cost. Trace amounts of transition elements chromium, titanium, vanadium, iron and zirconium, when in solution noticeably decrease the electrical conductivity of aluminum. For example, only 0.04% weight percent of chromium lowers the electrical conductivity by 3% IACS (Fig.2). When boron is added to aluminum, it reacts to form insoluble boron compounds of transition elements, and these have insignificant effect on conductivity.

AlB alloy has primarily two stable phases as AlB12 and AlB2. Both react instantaneously, with AlB2 reacting faster. AlB2 has hexagonal closed packed crystal structure with a=0.3006nm and c=0.3252nm, whereas AlB12 has tetragonal crystal structure with a=1.0161 nm and b=1.4238nm. Diborides form AlB2 are smaller than AlB12 which results in lower settling rate with high aspect ratio crystal flakes, with larger volumes of small particles are carried out of furnace. Sludge formation is reduced in the furnace.


AlB12 have slightly larger particle size because of high boron concentration of AlB12, which settles faster and results in reduced portion of transition elements borides are carried out of furnace. Frequent furnace cleanings may be required as higher concentration of settled particles.

Forms Std. Size (mm) Std. Weight (Kg)
Piglet 60x45x45  
Waffle plate   8 – 10
Ingot   6 – 8
Piglet Ingot Waffle plate
25 Kg gunny bag/500 Kg
Jumbo Bag (or as per
customer requirement)
1000 Kg jumbo bag or
strapping with palette (or as
per customer requirement)
 500 Kg strapping with palette
(or as per customer
requirement)

Stoichiometrically, an exact calculation for the required addition can be made based upon the transition elements concentrations. However, as per  commercial practice “rule of thumb” was to add boron in an amount equal to one half the total weight percent of Ti+V+Cr+Zr, and will result in slight amount of excess boron in the melt over and above that required to form insoluble borides.

Where, B= Total weight of AlB alloy required; P= conc. of AlB alloy %; M= wt. of aluminum to be treated kg; Ti+V+Cr+Zr= conc. of impurity element %;
The insoluble boride particles formed by the reaction between impurities and the boron tend to settle out of the metal and provide significant conductivity increase and excess boron inhibit the ability of grain refiner to yield reasonable grain size.

Use cool and dry place to store the material.

Material Safety Data Sheet can be supplied on demand. Material is not hazardous but normal safety precautions to be followed.