Golf club design technology's advancement owes largely to the development of applications in advanced materials. Recent composite material applications and new alloys are prevalent in the world of golf clubs.

Composite Materials - Composite materials for graphite shafts have changed particularly the way designers develop drivers. Light and strong shafts with consistent properties are essential to today's driver. Graphite shafts usually consist of a ceramic material such as carbon or glass fibers embedded within a matrix. The most widely used type of graphite shaft is epoxy based composite, and the fibers make up about 60 percent by volume. Currently, fabricating composite materials is still a labor-intensive process, and that makes graphite shaft clubs more expensive than those with steel shafts. Technological advancement in steel shaft, however, has also been witnessed (see "shaft").

Titanium Alloys - As you are well aware, the most significant change in golf equipment material may be the use of titanium (see "driver"). Pure titanium (Ti) is rather soft, as is iron, and not strong enough for golf club applications except for face inserts. Its specific gravity, weight of material compared to equal volume of water, is 4.42 and much lighter than iron (7.86) or its alloys such as the stainless steel. There are basically two types of titanium alloys used for golf clubs. 6-4 titanium which includes 6% of aluminum (Al), and 4% of vanadium (Va) are used exclusively for cast clubs, while beta titanium (15% Va, 3% Cr, 3% Al, 3% Ni) are useful for forging.

Tungsten - With the specific gravity of 19.5, tungsten (W) is roughly 2.5 times heavier than steel, and a little more than 4 times heavier than titanium. This material has been known for its filament applications for a long time. But for golf clubs, it is primarily used as weight for shifting the center of gravity lower and/or deeper, and/or for the perimeter design. Also, the metal is used for golf balls either for the core or as powder for the composite layer underneath the cover.

Mild Steels and Stainless Steels - While cast iron, which contains amounts of carbon varying from 2 to 4 percent is relatively hard, mild steel with low carbon concentration (0.1% - 0.3%) is soft, and therefore used for forged iron club-heads. Traditionally, forged irons are plated with chromium (Cr) for the rust protection; however, for a softer feel nickel (Ni) plating has become popular recently. Also, stainless steel such as SUS 630 (17% Cr, 4% Ni) , which is often called 17-4 steel, used first by Ping for the famous cavity-back cast irons, is widely used for both irons and woods. SUS 304 (18% Cr, 8% Ni) another stainless steel, which is softer than SUS 630, is also used for cast irons. Clubs made of SUS 304 provide much softer feel, and are even bendable. C450 stainless steel is introduced recently by Taylor Made (SuperSteel) is considered to be stronger that the foregoing stainless steels, which allows the thinner wall design.

Other Metals - Other materials used for club-heads include beryllium copper (Cu + 1%-2.5% Be), which is 6-7% heavier than stainless steel and is often used for wedges. Also, since aluminum's specific gravity is only 2.8 and very light, aluminum alloys, particularly 7075-6A Aluminum (Al + Pb 4%-6%, Mg 2%-3%), are used for drivers because of the lightweight, strength and processability. In addition, due to its softer feel, nickel has become a popular material for golf clubs - in the form of nickel plating and alloys. Maraging steel, which is used recently as a material for inserts since it is believed strong and hard, is low-carbon martensitic steel which contains up to 25% nickel and in which hardening precipitates are formed by aging. For more detailed information, there is a perfect website, Principal Metals Online,  explaining not only specifications of metals but also Chemical Data and Principal Design Features.

Materials for Putters - Stainless steel, brass, copper and bronze were traditionally used for putters. Today other softer materials, including polymeric materials, are also used for putters. For example, one of the leading manufactures, Ping, offers 7 different materials to choose from. They are stainless steel, bronze, beryllium copper, beryllium nickel, elastomer insert, and aluminum inserts as well as laminated maple (see below).

Ping's line of materials for putters (Source: Ping)

Elastomer - It is defined as any synthetic polymeric substance that exhibits, to some extent, the properties of rubber, especially its elasticity and flexibility. Elastomer therefore provides a higher damping coefficient. Recent models use elastomer either as an insert itself (surface material) or as a cushioning layer behind the metal insert. The number of materials used for putters has multipled. Titleist, for instance, says that Teryllium alloy used for the new Scotty Cameron Teryllium Putter is a unique metal formed of 12 different alloys (different from tellurium). Likewise, it is next to impossible to introduce all materials used for putter in this type of space. In many cases, these new materials are used for softer feel and greater forgiveness by enlarging the sweet spot and larger inertia moment, whereby a golf ball stricken off the center of the club face would gain both distance and direction closer to the intended target.