From BiblePortal Wikipedia

Webster's Dictionary [1]

(1): (v. t.) Admixture of anything which lessens the value or detracts from; as, no happiness is without alloy.

(2): (v. t.) A baser metal mixed with a finer.

(3): (v. t.) To form a metallic compound.

(4): (v. t.) Any combination or compound of metals fused together; a mixture of metals; for example, brass, which is an alloy of copper and zinc. But when mercury is one of the metals, the compound is called an amalgam.

(5): (v. t.) The quality, or comparative purity, of gold or silver; fineness.

(6): (v. t.) To abate, impair, or debase by mixture; to allay; as, to alloy pleasure with misfortunes.

(7): (v. t.) To reduce the purity of by mixing with a less valuable substance; as, to alloy gold with silver or copper, or silver with copper.

(8): (v. t.) To mix, as metals, so as to form a compound.

Hastings' Dictionary of the Bible [2]

Alloy . RVm [Note: Revised Version margin.] (  Isaiah 1:25 ) for EV [Note: English Version.] ‘tin.’ See Mining and Metals.

International Standard Bible Encyclopedia [3]

a - loi ´ (בּדיל , bedhı̄l ): In  Isaiah 1:25 the Revised Version, margin; translated "tin" in the text. Elsewhere in both versions bedhı̄l is translated Tin (which see).